diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/CollisionDetector.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/CollisionDetector.java
new file mode 100644
index 0000000..0913d03
--- /dev/null
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/CollisionDetector.java
@@ -0,0 +1,50 @@
+/*
+ * Copyright 2016 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.yangutils.datamodel;
+
+import org.onosproject.yangutils.datamodel.exceptions.DataModelException;
+import org.onosproject.yangutils.utils.YangConstructType;
+
+/**
+ * Abstraction of YANG collision function. Abstracted to unify the collision
+ * detection functionality.
+ */
+public interface CollisionDetector {
+    /**
+     * Checks for the colliding child.
+     *
+     * @param identifierName name of identifier for which collision to be
+     *            checked
+     * @param dataType type of the YANG construct for which collision to be
+     *            checked
+     * @throws DataModelException if there is any collision in YANG rules in
+     *             parsed data, corresponding exception should be thrown
+     */
+    void detectCollidingChild(String identifierName, YangConstructType dataType) throws DataModelException;
+
+    /**
+     * Check for the self collision.
+     *
+     * @param identifierName name of identifier for which collision to be
+     *            checked
+     * @param dataType type of the YANG construct for which collision to be
+     *            checked
+     * @throws DataModelException if there is any collision in YANG rules in
+     *             parsed data, corresponding exception should be thrown
+     */
+    void detectSelfCollision(String identifierName, YangConstructType dataType) throws DataModelException;
+}
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangAugment.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangAugment.java
index 378eaf4..30d4978 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangAugment.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangAugment.java
@@ -20,7 +20,7 @@
 
 import org.onosproject.yangutils.datamodel.exceptions.DataModelException;
 import org.onosproject.yangutils.parser.Parsable;
-import org.onosproject.yangutils.parser.ParsableDataType;
+import org.onosproject.yangutils.utils.YangConstructType;
 import org.onosproject.yangutils.translator.CachedFileHandle;
 
 /*-
@@ -85,7 +85,7 @@
     private String targetNode;
 
     /**
-     * description of augment.
+     * Description of augment.
      */
     private String description;
 
@@ -100,7 +100,7 @@
     private List<YangLeafList> listOfLeafList;
 
     /**
-     * reference.
+     * Reference of the YANG augment.
      */
     private String reference;
 
@@ -110,7 +110,7 @@
     private YangStatusType status;
 
     /**
-     * package of the generated java code.
+     * Package of the generated java code.
      */
     private String pkg;
 
@@ -124,7 +124,7 @@
     /**
      * Get the augmented node.
      *
-     * @return the augmented node.
+     * @return the augmented node
      */
     public String getTargetNode() {
         return targetNode;
@@ -133,7 +133,7 @@
     /**
      * Set the augmented node.
      *
-     * @param targetNode the augmented node.
+     * @param targetNode the augmented node
      */
     public void setTargetNode(String targetNode) {
         this.targetNode = targetNode;
@@ -142,7 +142,7 @@
     /**
      * Get the description.
      *
-     * @return the description.
+     * @return the description
      */
     @Override
     public String getDescription() {
@@ -152,7 +152,7 @@
     /**
      * Set the description.
      *
-     * @param description set the description.
+     * @param description set the description
      */
     @Override
     public void setDescription(String description) {
@@ -162,7 +162,7 @@
     /**
      * Get the list of leaves.
      *
-     * @return the list of leaves.
+     * @return the list of leaves
      */
     @Override
     public List<YangLeaf> getListOfLeaf() {
@@ -172,7 +172,7 @@
     /**
      * Set the list of leaves.
      *
-     * @param leafsList the list of leaf to set.
+     * @param leafsList the list of leaf to set
      */
     private void setListOfLeaf(List<YangLeaf> leafsList) {
         listOfLeaf = leafsList;
@@ -181,7 +181,7 @@
     /**
      * Add a leaf.
      *
-     * @param leaf the leaf to be added.
+     * @param leaf the leaf to be added
      */
     @Override
     public void addLeaf(YangLeaf leaf) {
@@ -195,7 +195,7 @@
     /**
      * Get the list of leaf-list.
      *
-     * @return the list of leaf-list.
+     * @return the list of leaf-list
      */
     @Override
     public List<YangLeafList> getListOfLeafList() {
@@ -205,7 +205,7 @@
     /**
      * Set the list of leaf-list.
      *
-     * @param listOfLeafList the list of leaf-list to set.
+     * @param listOfLeafList the list of leaf-list to set
      */
     private void setListOfLeafList(List<YangLeafList> listOfLeafList) {
         this.listOfLeafList = listOfLeafList;
@@ -214,7 +214,7 @@
     /**
      * Add a leaf-list.
      *
-     * @param leafList the leaf-list to be added.
+     * @param leafList the leaf-list to be added
      */
     @Override
     public void addLeafList(YangLeafList leafList) {
@@ -228,7 +228,7 @@
     /**
      * Get the textual reference.
      *
-     * @return the reference.
+     * @return the reference
      */
     @Override
     public String getReference() {
@@ -238,7 +238,7 @@
     /**
      * Set the textual reference.
      *
-     * @param reference the reference to set.
+     * @param reference the reference to set
      */
     @Override
     public void setReference(String reference) {
@@ -248,7 +248,7 @@
     /**
      * Get the status.
      *
-     * @return the status.
+     * @return the status
      */
     @Override
     public YangStatusType getStatus() {
@@ -258,7 +258,7 @@
     /**
      * Set the status.
      *
-     * @param status the status to set.
+     * @param status the status to set
      */
     @Override
     public void setStatus(YangStatusType status) {
@@ -268,17 +268,17 @@
     /**
      * Returns the type of the data as belongs-to.
      *
-     * @return returns AUGMENT_DATA.
+     * @return returns AUGMENT_DATA
      */
     @Override
-    public ParsableDataType getParsableDataType() {
-        return ParsableDataType.AUGMENT_DATA;
+    public YangConstructType getYangConstructType() {
+        return YangConstructType.AUGMENT_DATA;
     }
 
     /**
      * Validate the data on entering the corresponding parse tree node.
      *
-     * @throws DataModelException a violation of data model rules.
+     * @throws DataModelException a violation of data model rules
      */
     @Override
     public void validateDataOnEntry() throws DataModelException {
@@ -288,7 +288,7 @@
     /**
      * Validate the data on exiting the corresponding parse tree node.
      *
-     * @throws DataModelException a violation of data model rules.
+     * @throws DataModelException a violation of data model rules
      */
     @Override
     public void validateDataOnExit() throws DataModelException {
@@ -298,7 +298,7 @@
     /**
      * Get the target nodes name where the augmentation is being done.
      *
-     * @return target nodes name where the augmentation is being done.
+     * @return target nodes name where the augmentation is being done
      */
     @Override
     public String getName() {
@@ -308,7 +308,7 @@
     /**
      * Set the target nodes name where the augmentation is being done.
      *
-     * @param name target nodes name where the augmentation is being done.
+     * @param name target nodes name where the augmentation is being done
      */
     @Override
     public void setName(String name) {
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangBelongsTo.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangBelongsTo.java
index a4a5cae..b3b718f 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangBelongsTo.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangBelongsTo.java
@@ -17,7 +17,7 @@
 
 import org.onosproject.yangutils.datamodel.exceptions.DataModelException;
 import org.onosproject.yangutils.parser.Parsable;
-import org.onosproject.yangutils.parser.ParsableDataType;
+import org.onosproject.yangutils.utils.YangConstructType;
 
 /*-
  *   Reference 6020.
@@ -94,7 +94,7 @@
     /**
      * Get the prefix.
      *
-     * @return the prefix.
+     * @return the prefix
      */
     public String getPrefix() {
         return prefix;
@@ -115,14 +115,14 @@
      * @return ParsedDataType returns BELONGS_TO_DATA
      */
     @Override
-    public ParsableDataType getParsableDataType() {
-        return ParsableDataType.BELONGS_TO_DATA;
+    public YangConstructType getYangConstructType() {
+        return YangConstructType.BELONGS_TO_DATA;
     }
 
     /**
      * Validate the data on entering the corresponding parse tree node.
      *
-     * @throws DataModelException a violation of data model rules.
+     * @throws DataModelException a violation of data model rules
      */
     @Override
     public void validateDataOnEntry() throws DataModelException {
@@ -132,7 +132,7 @@
     /**
      * Validate the data on exiting the corresponding parse tree node.
      *
-     * @throws DataModelException a violation of data model rules.
+     * @throws DataModelException a violation of data model rules
      */
     @Override
     public void validateDataOnExit() throws DataModelException {
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangBit.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangBit.java
index 77f19c1..47956e6 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangBit.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangBit.java
@@ -18,7 +18,7 @@
 
 import org.onosproject.yangutils.datamodel.exceptions.DataModelException;
 import org.onosproject.yangutils.parser.Parsable;
-import org.onosproject.yangutils.parser.ParsableDataType;
+import org.onosproject.yangutils.utils.YangConstructType;
 
 import java.util.Objects;
 
@@ -83,7 +83,7 @@
     /**
      * Returns bit name.
      *
-     * @return the bit name.
+     * @return the bit name
      */
     public String getBitName() {
         return bitName;
@@ -92,7 +92,7 @@
     /**
      * Set the bit name.
      *
-     * @param bitName the bit name to set.
+     * @param bitName the bit name to set
      */
     public void setBitName(String bitName) {
         this.bitName = bitName;
@@ -101,7 +101,7 @@
     /**
      * Returns description.
      *
-     * @return the description.
+     * @return the description
      */
     @Override
     public String getDescription() {
@@ -111,7 +111,7 @@
     /**
      * Set the description.
      *
-     * @param description set the description.
+     * @param description set the description
      */
     @Override
     public void setDescription(String description) {
@@ -121,7 +121,7 @@
     /**
      * Returns textual reference.
      *
-     * @return the reference.
+     * @return the reference
      */
     @Override
     public String getReference() {
@@ -131,7 +131,7 @@
     /**
      * Set the textual reference.
      *
-     * @param reference the reference to set.
+     * @param reference the reference to set
      */
     @Override
     public void setReference(String reference) {
@@ -141,7 +141,7 @@
     /**
      * Returns status.
      *
-     * @return the status.
+     * @return the status
      */
     @Override
     public YangStatusType getStatus() {
@@ -151,7 +151,7 @@
     /**
      * Set the status.
      *
-     * @param status the status to set.
+     * @param status the status to set
      */
     @Override
     public void setStatus(YangStatusType status) {
@@ -170,7 +170,7 @@
     /**
      * Set the bit position.
      *
-     * @param position the position to set.
+     * @param position the position to set
      */
     public void setPosition(int position) {
         this.position = position;
@@ -182,8 +182,8 @@
      * @return ParsedDataType returns BIT_DATA
      */
     @Override
-    public ParsableDataType getParsableDataType() {
-        return ParsableDataType.BIT_DATA;
+    public YangConstructType getYangConstructType() {
+        return YangConstructType.BIT_DATA;
     }
 
     @Override
@@ -206,7 +206,7 @@
     /**
      * Validate the data on entering the corresponding parse tree node.
      *
-     * @throws DataModelException a violation of data model rules.
+     * @throws DataModelException a violation of data model rules
      */
     @Override
     public void validateDataOnEntry() throws DataModelException {
@@ -216,7 +216,7 @@
     /**
      * Validate the data on exiting the corresponding parse tree node.
      *
-     * @throws DataModelException a violation of data model rules.
+     * @throws DataModelException a violation of data model rules
      */
     @Override
     public void validateDataOnExit() throws DataModelException {
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangBits.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangBits.java
index 54898a4..dbf0531 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangBits.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangBits.java
@@ -21,7 +21,7 @@
 
 import org.onosproject.yangutils.datamodel.exceptions.DataModelException;
 import org.onosproject.yangutils.parser.Parsable;
-import org.onosproject.yangutils.parser.ParsableDataType;
+import org.onosproject.yangutils.utils.YangConstructType;
 
 /*
  * Reference RFC 6020.
@@ -70,12 +70,13 @@
     /**
      * Add bit info.
      *
-     * @param bitInfo the bit information to be added.
-     * @throws DataModelException due to violation in data model rules.
+     * @param bitInfo the bit information to be added
+     * @throws DataModelException due to violation in data model rules
      */
     public void addBitInfo(YangBit bitInfo) throws DataModelException {
         if (!getBitSet().add(bitInfo)) {
-            throw new DataModelException("YANG Bit already exists");
+            throw new DataModelException("YANG file error: Duplicate identifier detected, same as bit \""
+                    + bitInfo.getBitName() + "\"");
         }
     }
 
@@ -85,14 +86,14 @@
      * @return ParsedDataType returns BITS_DATA
      */
     @Override
-    public ParsableDataType getParsableDataType() {
-        return ParsableDataType.BITS_DATA;
+    public YangConstructType getYangConstructType() {
+        return YangConstructType.BITS_DATA;
     }
 
     /**
      * Returns the bits name.
      *
-     * @return name of the bits.
+     * @return name of the bits
      */
     public String getBitsName() {
         return bitsName;
@@ -101,7 +102,7 @@
     /**
      * Set bits name.
      *
-     * @param bitsName bit name to be set.
+     * @param bitsName bit name to be set
      */
     public void setBitsName(String bitsName) {
         this.bitsName = bitsName;
@@ -110,7 +111,7 @@
     /**
      * Validate the data on entering the corresponding parse tree node.
      *
-     * @throws DataModelException a violation of data model rules.
+     * @throws DataModelException a violation of data model rules
      */
     @Override
     public void validateDataOnEntry() throws DataModelException {
@@ -120,7 +121,7 @@
     /**
      * Validate the data on exiting the corresponding parse tree node.
      *
-     * @throws DataModelException a violation of data model rules.
+     * @throws DataModelException a violation of data model rules
      */
     @Override
     public void validateDataOnExit() throws DataModelException {
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangCase.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangCase.java
index dc9f36b..b9da3c2 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangCase.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangCase.java
@@ -15,14 +15,16 @@
  */
 package org.onosproject.yangutils.datamodel;
 
+import org.onosproject.yangutils.datamodel.exceptions.DataModelException;
+import static org.onosproject.yangutils.datamodel.utils.DataModelUtils.detectCollidingChildUtil;
+import org.onosproject.yangutils.parser.Parsable;
+import org.onosproject.yangutils.translator.CachedFileHandle;
+import org.onosproject.yangutils.utils.YangConstructType;
+import static org.onosproject.yangutils.utils.YangConstructType.CASE_DATA;
+
 import java.util.LinkedList;
 import java.util.List;
 
-import org.onosproject.yangutils.datamodel.exceptions.DataModelException;
-import org.onosproject.yangutils.parser.Parsable;
-import org.onosproject.yangutils.parser.ParsableDataType;
-import org.onosproject.yangutils.translator.CachedFileHandle;
-
 /*-
  * Reference RFC 6020.
  *
@@ -90,7 +92,7 @@
  * Data model node to maintain information defined in YANG case.
  */
 public class YangCase extends YangNode
-        implements YangLeavesHolder, YangCommonInfo, Parsable {
+        implements YangLeavesHolder, YangCommonInfo, Parsable, CollisionDetector {
 
     /**
      * Case name.
@@ -100,7 +102,7 @@
     // TODO: default field identification for the case
 
     /**
-     * Description of container.
+     * Description of case.
      */
     private String description;
 
@@ -125,7 +127,7 @@
     private YangStatusType status;
 
     /**
-     * package of the generated java code.
+     * Package of the generated java code.
      */
     private String pkg;
 
@@ -139,7 +141,7 @@
     /**
      * Get the case name.
      *
-     * @return case name.
+     * @return case name
      */
     @Override
     public String getName() {
@@ -149,7 +151,7 @@
     /**
      * Set the case name.
      *
-     * @param name case name.
+     * @param name case name
      */
     @Override
     public void setName(String name) {
@@ -159,7 +161,7 @@
     /**
      * Get the description.
      *
-     * @return the description.
+     * @return the description
      */
     @Override
     public String getDescription() {
@@ -169,7 +171,7 @@
     /**
      * Set the description.
      *
-     * @param description set the description.
+     * @param description set the description
      */
     @Override
     public void setDescription(String description) {
@@ -179,7 +181,7 @@
     /**
      * Get the list of leaves.
      *
-     * @return the list of leaves.
+     * @return the list of leaves
      */
     @Override
     public List<YangLeaf> getListOfLeaf() {
@@ -189,7 +191,7 @@
     /**
      * Set the list of leaves.
      *
-     * @param leafsList the list of leaf to set.
+     * @param leafsList the list of leaf to set
      */
     private void setListOfLeaf(List<YangLeaf> leafsList) {
         listOfLeaf = leafsList;
@@ -198,7 +200,7 @@
     /**
      * Add a leaf.
      *
-     * @param leaf the leaf to be added.
+     * @param leaf the leaf to be added
      */
     @Override
     public void addLeaf(YangLeaf leaf) {
@@ -212,7 +214,7 @@
     /**
      * Get the list of leaf-list.
      *
-     * @return the list of leaf-list.
+     * @return the list of leaf-list
      */
     @Override
     public List<YangLeafList> getListOfLeafList() {
@@ -222,7 +224,7 @@
     /**
      * Set the list of leaf-list.
      *
-     * @param listOfLeafList the list of leaf-list to set.
+     * @param listOfLeafList the list of leaf-list to set
      */
     private void setListOfLeafList(List<YangLeafList> listOfLeafList) {
         this.listOfLeafList = listOfLeafList;
@@ -231,7 +233,7 @@
     /**
      * Add a leaf-list.
      *
-     * @param leafList the leaf-list to be added.
+     * @param leafList the leaf-list to be added
      */
     @Override
     public void addLeafList(YangLeafList leafList) {
@@ -245,7 +247,7 @@
     /**
      * Get the textual reference.
      *
-     * @return the reference.
+     * @return the reference
      */
     @Override
     public String getReference() {
@@ -255,7 +257,7 @@
     /**
      * Set the textual reference.
      *
-     * @param reference the reference to set.
+     * @param reference the reference to set
      */
     @Override
     public void setReference(String reference) {
@@ -265,7 +267,7 @@
     /**
      * Get the status.
      *
-     * @return the status.
+     * @return the status
      */
     @Override
     public YangStatusType getStatus() {
@@ -275,7 +277,7 @@
     /**
      * Set the status.
      *
-     * @param status the status to set.
+     * @param status the status to set
      */
     @Override
     public void setStatus(YangStatusType status) {
@@ -288,14 +290,14 @@
      * @return returns CASE_DATA
      */
     @Override
-    public ParsableDataType getParsableDataType() {
-        return ParsableDataType.CASE_DATA;
+    public YangConstructType getYangConstructType() {
+        return YangConstructType.CASE_DATA;
     }
 
     /**
      * Validate the data on entering the corresponding parse tree node.
      *
-     * @throws DataModelException a violation of data model rules.
+     * @throws DataModelException a violation of data model rules
      */
     @Override
     public void validateDataOnEntry() throws DataModelException {
@@ -305,7 +307,7 @@
     /**
      * Validate the data on exiting the corresponding parse tree node.
      *
-     * @throws DataModelException a violation of data model rules.
+     * @throws DataModelException a violation of data model rules
      */
     @Override
     public void validateDataOnExit() throws DataModelException {
@@ -361,6 +363,30 @@
     @Override
     public void setFileHandle(CachedFileHandle fileHandle) {
         // TODO Auto-generated method stub
+    }
 
+    @Override
+    public void detectCollidingChild(String identifierName, YangConstructType dataType) throws DataModelException {
+        if ((this.getParent() == null) || (!(this.getParent() instanceof YangChoice))) {
+            throw new DataModelException("Internal Data Model Tree Error: Invalid/Missing holder in case " +
+                    this.getName());
+        }
+        // Traverse up in tree to ask parent choice start collision detection.
+        ((CollisionDetector) this.getParent()).detectCollidingChild(identifierName, dataType);
+    }
+
+    @Override
+    public void detectSelfCollision(String identifierName, YangConstructType dataType) throws DataModelException {
+
+        if (dataType == CASE_DATA) {
+            if (this.getName().equals(identifierName)) {
+                throw new DataModelException("YANG File Error: Identifier collision detected in case \"" +
+                        this.getName() + "\"");
+            }
+            return;
+        }
+
+        // Asks helper to detect colliding child.
+        detectCollidingChildUtil(identifierName, dataType, this);
     }
 }
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangChoice.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangChoice.java
index be47039..440ca57 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangChoice.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangChoice.java
@@ -15,13 +15,11 @@
  */
 package org.onosproject.yangutils.datamodel;
 
-import java.util.LinkedList;
-import java.util.List;
-
 import org.onosproject.yangutils.datamodel.exceptions.DataModelException;
 import org.onosproject.yangutils.parser.Parsable;
-import org.onosproject.yangutils.parser.ParsableDataType;
 import org.onosproject.yangutils.translator.CachedFileHandle;
+import org.onosproject.yangutils.utils.YangConstructType;
+import static org.onosproject.yangutils.utils.YangConstructType.CHOICE_DATA;
 
 /*-
  * Reference RFC 6020.
@@ -61,7 +59,7 @@
 /**
  * Data model node to maintain information defined in YANG choice.
  */
-public class YangChoice extends YangNode implements YangCommonInfo, Parsable {
+public class YangChoice extends YangNode implements YangCommonInfo, Parsable, CollisionDetector {
 
     /**
      * Name of choice.
@@ -69,11 +67,6 @@
     private String name;
 
     /**
-     * List of cases for the current choice.
-     */
-    private List<YangCase> caseList;
-
-    /**
      * If the choice represents config data.
      */
     private boolean isConfig;
@@ -105,7 +98,7 @@
     private String defaultCase;
 
     /**
-     * Description.
+     * Description of choice.
      */
     private String description;
 
@@ -131,7 +124,7 @@
     private String mandatory;
 
     /**
-     * reference of the choice.
+     * Reference of the choice.
      */
     private String reference;
 
@@ -141,13 +134,15 @@
     private YangStatusType status;
 
     /**
-     * Create a Choice node.
+     * Create a choice node.
      */
     public YangChoice() {
         super(YangNodeType.CHOICE_NODE);
     }
 
-    /* (non-Javadoc)
+    /*
+     * (non-Javadoc)
+     *
      * @see org.onosproject.yangutils.datamodel.YangNode#getName()
      */
     @Override
@@ -155,8 +150,11 @@
         return name;
     }
 
-    /* (non-Javadoc)
-     * @see org.onosproject.yangutils.datamodel.YangNode#setName(java.lang.String)
+    /*
+     * (non-Javadoc)
+     *
+     * @see
+     * org.onosproject.yangutils.datamodel.YangNode#setName(java.lang.String)
      */
     @Override
     public void setName(String name) {
@@ -164,40 +162,9 @@
     }
 
     /**
-     * Get the list of cases.
-     *
-     * @return the case list
-     */
-    public List<YangCase> getCaseList() {
-        return caseList;
-    }
-
-    /**
-     * Set the list of cases.
-     *
-     * @param caseList list of cases.
-     */
-    private void setCaseList(List<YangCase> caseList) {
-        this.caseList = caseList;
-    }
-
-    /**
-     * Add a case.
-     *
-     * @param newCase new case for the choice
-     */
-    public void addCase(YangCase newCase) {
-        if (getCaseList() == null) {
-            setCaseList(new LinkedList<YangCase>());
-        }
-
-        getCaseList().add(newCase);
-    }
-
-    /**
      * Get config flag.
      *
-     * @return the config flag.
+     * @return the config flag
      */
     public boolean isConfig() {
         return isConfig;
@@ -206,7 +173,7 @@
     /**
      * Set config flag.
      *
-     * @param isCfg the config flag.
+     * @param isCfg the config flag
      */
     public void setConfig(boolean isCfg) {
         isConfig = isCfg;
@@ -215,7 +182,7 @@
     /**
      * Get the default case.
      *
-     * @return the default case.
+     * @return the default case
      */
     public String getDefaultCase() {
         return defaultCase;
@@ -233,7 +200,7 @@
     /**
      * Get the mandatory status.
      *
-     * @return the mandatory status.
+     * @return the mandatory status
      */
     public String getMandatory() {
         return mandatory;
@@ -242,7 +209,7 @@
     /**
      * Set the mandatory status.
      *
-     * @param mandatory the mandatory status.
+     * @param mandatory the mandatory status
      */
     public void setMandatory(String mandatory) {
         this.mandatory = mandatory;
@@ -251,7 +218,7 @@
     /**
      * Get the description.
      *
-     * @return the description.
+     * @return the description
      */
     @Override
     public String getDescription() {
@@ -261,7 +228,7 @@
     /**
      * Set the description.
      *
-     * @param description set the description.
+     * @param description set the description
      */
     @Override
     public void setDescription(String description) {
@@ -271,7 +238,7 @@
     /**
      * Get the textual reference.
      *
-     * @return the reference.
+     * @return the reference
      */
     @Override
     public String getReference() {
@@ -281,7 +248,7 @@
     /**
      * Set the textual reference.
      *
-     * @param reference the reference to set.
+     * @param reference the reference to set
      */
     @Override
     public void setReference(String reference) {
@@ -291,7 +258,7 @@
     /**
      * Get the status.
      *
-     * @return the status.
+     * @return the status
      */
     @Override
     public YangStatusType getStatus() {
@@ -301,7 +268,7 @@
     /**
      * Set the status.
      *
-     * @param status the status to set.
+     * @param status the status to set
      */
     @Override
     public void setStatus(YangStatusType status) {
@@ -314,14 +281,14 @@
      * @return returns CHOICE_DATA
      */
     @Override
-    public ParsableDataType getParsableDataType() {
-        return ParsableDataType.CHOICE_DATA;
+    public YangConstructType getYangConstructType() {
+        return YangConstructType.CHOICE_DATA;
     }
 
     /**
      * Validate the data on entering the corresponding parse tree node.
      *
-     * @throws DataModelException a violation of data model rules.
+     * @throws DataModelException a violation of data model rules
      */
     @Override
     public void validateDataOnEntry() throws DataModelException {
@@ -331,14 +298,16 @@
     /**
      * Validate the data on exiting the corresponding parse tree node.
      *
-     * @throws DataModelException a violation of data model rules.
+     * @throws DataModelException a violation of data model rules
      */
     @Override
     public void validateDataOnExit() throws DataModelException {
         // TODO auto-generated method stub, to be implemented by parser
     }
 
-    /* (non-Javadoc)
+    /*
+     * (non-Javadoc)
+     *
      * @see org.onosproject.yangutils.datamodel.YangNode#getPackage()
      */
     @Override
@@ -347,8 +316,11 @@
         return null;
     }
 
-    /* (non-Javadoc)
-     * @see org.onosproject.yangutils.datamodel.YangNode#setPackage(java.lang.String)
+    /*
+     * (non-Javadoc)
+     *
+     * @see
+     * org.onosproject.yangutils.datamodel.YangNode#setPackage(java.lang.String)
      */
     @Override
     public void setPackage(String pkg) {
@@ -356,8 +328,12 @@
 
     }
 
-    /* (non-Javadoc)
-     * @see org.onosproject.yangutils.translator.CodeGenerator#generateJavaCodeEntry()
+    /*
+     * (non-Javadoc)
+     *
+     * @see
+     * org.onosproject.yangutils.translator.CodeGenerator#generateJavaCodeEntry(
+     * )
      */
     @Override
     public void generateJavaCodeEntry() {
@@ -365,8 +341,11 @@
 
     }
 
-    /* (non-Javadoc)
-     * @see org.onosproject.yangutils.translator.CodeGenerator#generateJavaCodeExit()
+    /*
+     * (non-Javadoc)
+     *
+     * @see
+     * org.onosproject.yangutils.translator.CodeGenerator#generateJavaCodeExit()
      */
     @Override
     public void generateJavaCodeExit() {
@@ -385,4 +364,36 @@
         // TODO Auto-generated method stub
 
     }
+
+    @Override
+    public void detectCollidingChild(String identifierName, YangConstructType dataType) throws DataModelException {
+
+        YangNode node = this.getChild();
+        while ((node != null)) {
+            if (node instanceof CollisionDetector) {
+                ((CollisionDetector) node).detectSelfCollision(identifierName, dataType);
+            }
+            node = node.getNextSibling();
+        }
+    }
+
+    @Override
+    public void detectSelfCollision(String identifierName, YangConstructType dataType) throws DataModelException {
+
+        if (dataType == CHOICE_DATA) {
+            if (this.getName().equals(identifierName)) {
+                throw new DataModelException("YANG file error: Identifier collision detected in choice \"" +
+                        this.getName() + "\"");
+            }
+            return;
+        }
+
+        YangNode node = this.getChild();
+        while ((node != null)) {
+            if (node instanceof CollisionDetector) {
+                ((CollisionDetector) node).detectSelfCollision(identifierName, dataType);
+            }
+            node = node.getNextSibling();
+        }
+    }
 }
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangContainer.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangContainer.java
index 99baf4a..d251479 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangContainer.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangContainer.java
@@ -21,8 +21,9 @@
 import java.util.List;
 
 import org.onosproject.yangutils.datamodel.exceptions.DataModelException;
+import static org.onosproject.yangutils.datamodel.utils.DataModelUtils.detectCollidingChildUtil;
 import org.onosproject.yangutils.parser.Parsable;
-import org.onosproject.yangutils.parser.ParsableDataType;
+import org.onosproject.yangutils.utils.YangConstructType;
 import org.onosproject.yangutils.translator.CachedFileHandle;
 import org.onosproject.yangutils.translator.GeneratedFileType;
 import org.onosproject.yangutils.translator.tojava.utils.JavaIdentifierSyntax;
@@ -90,7 +91,7 @@
 /**
  * Data model node to maintain information defined in YANG container.
  */
-public class YangContainer extends YangNode implements YangLeavesHolder, YangCommonInfo, Parsable {
+public class YangContainer extends YangNode implements YangLeavesHolder, YangCommonInfo, Parsable, CollisionDetector {
 
     /**
      * Name of the container.
@@ -153,7 +154,7 @@
     /**
      * Get the YANG name of container.
      *
-     * @return the name of container as defined in YANG file.
+     * @return the name of container as defined in YANG file
      */
     @Override
     public String getName() {
@@ -163,7 +164,7 @@
     /**
      * Set the YANG name of container.
      *
-     * @param name the name of container as defined in YANG file.
+     * @param name the name of container as defined in YANG file
      */
     @Override
     public void setName(String name) {
@@ -182,7 +183,7 @@
     /**
      * Set the config flag.
      *
-     * @param isCfg the config flag.
+     * @param isCfg the config flag
      */
     public void setConfig(boolean isCfg) {
         isConfig = isCfg;
@@ -191,7 +192,7 @@
     /**
      * Get the description.
      *
-     * @return the description.
+     * @return the description
      */
     @Override
     public String getDescription() {
@@ -201,7 +202,7 @@
     /**
      * Set the description.
      *
-     * @param description set the description.
+     * @param description set the description
      */
     @Override
     public void setDescription(String description) {
@@ -211,7 +212,7 @@
     /**
      * Get the list of leaves.
      *
-     * @return the list of leaves.
+     * @return the list of leaves
      */
     @Override
     public List<YangLeaf> getListOfLeaf() {
@@ -221,7 +222,7 @@
     /**
      * Set the list of leaves.
      *
-     * @param leafsList the list of leaf to set.
+     * @param leafsList the list of leaf to set
      */
     private void setListOfLeaf(List<YangLeaf> leafsList) {
         listOfLeaf = leafsList;
@@ -230,7 +231,7 @@
     /**
      * Add a leaf.
      *
-     * @param leaf the leaf to be added.
+     * @param leaf the leaf to be added
      */
     @Override
     public void addLeaf(YangLeaf leaf) {
@@ -244,7 +245,7 @@
     /**
      * Get the list of leaf-list.
      *
-     * @return the list of leaf-list.
+     * @return the list of leaf-list
      */
     @Override
     public List<YangLeafList> getListOfLeafList() {
@@ -254,7 +255,7 @@
     /**
      * Set the list of leaf-list.
      *
-     * @param listOfLeafList the list of leaf-list to set.
+     * @param listOfLeafList the list of leaf-list to set
      */
     private void setListOfLeafList(List<YangLeafList> listOfLeafList) {
         this.listOfLeafList = listOfLeafList;
@@ -263,7 +264,7 @@
     /**
      * Add a leaf-list.
      *
-     * @param leafList the leaf-list to be added.
+     * @param leafList the leaf-list to be added
      */
     @Override
     public void addLeafList(YangLeafList leafList) {
@@ -277,7 +278,7 @@
     /**
      * Get the presence string if present.
      *
-     * @return the isPressence.
+     * @return the presence
      */
     public String getPresence() {
         return presence;
@@ -295,7 +296,7 @@
     /**
      * Get the textual reference.
      *
-     * @return the reference.
+     * @return the reference
      */
     @Override
     public String getReference() {
@@ -305,7 +306,7 @@
     /**
      * Set the textual reference.
      *
-     * @param reference the reference to set.
+     * @param reference the reference to set
      */
     @Override
     public void setReference(String reference) {
@@ -315,7 +316,7 @@
     /**
      * Get the status.
      *
-     * @return the status.
+     * @return the status
      */
     @Override
     public YangStatusType getStatus() {
@@ -325,7 +326,7 @@
     /**
      * Set the status.
      *
-     * @param status the status to set.
+     * @param status the status to set
      */
     @Override
     public void setStatus(YangStatusType status) {
@@ -355,17 +356,17 @@
     /**
      * Returns the type of the data.
      *
-     * @return returns CONTAINER_DATA.
+     * @return returns CONTAINER_DATA
      */
     @Override
-    public ParsableDataType getParsableDataType() {
-        return ParsableDataType.CONTAINER_DATA;
+    public YangConstructType getYangConstructType() {
+        return YangConstructType.CONTAINER_DATA;
     }
 
     /**
      * Validate the data on entering the corresponding parse tree node.
      *
-     * @throws DataModelException a violation of data model rules.
+     * @throws DataModelException a violation of data model rules
      */
     @Override
     public void validateDataOnEntry() throws DataModelException {
@@ -375,7 +376,7 @@
     /**
      * Validate the data on exiting the corresponding parse tree node.
      *
-     * @throws DataModelException a violation of data model rules.
+     * @throws DataModelException a violation of data model rules
      */
     @Override
     public void validateDataOnExit() throws DataModelException {
@@ -387,15 +388,18 @@
     }
 
     /**
-     * Sets the config's value to all leaf if leaf's config statement is not specified.
+     * Sets the config's value to all leaf if leaf's config statement is not
+     * specified.
      *
-     * @param leaves list of leaf attributes of container.
-     * @param leafLists list of leaf-list attributes of container.
+     * @param leaves list of leaf attributes of container
+     * @param leafLists list of leaf-list attributes of container
      */
     private void setDefaultConfigValueToChild(List<YangLeaf> leaves, List<YangLeafList> leafLists) {
 
-        /* If "config" is not specified, the default is the same as the parent
-            schema node's "config" value.*/
+        /*
+         * If "config" is not specified, the default is the same as the parent
+         * schema node's "config" value.
+         */
         if (leaves != null) {
             for (YangLeaf leaf : leaves) {
                 if (leaf.isConfig() == null) {
@@ -404,8 +408,10 @@
             }
         }
 
-        /* If "config" is not specified, the default is the same as the parent
-           schema node's "config" value.*/
+        /*
+         * If "config" is not specified, the default is the same as the parent
+         * schema node's "config" value.
+         */
         if (leafLists != null) {
             for (YangLeafList leafList : leafLists) {
                 if (leafList.isConfig() == null) {
@@ -418,14 +424,16 @@
     /**
      * Validates config statement of container.
      *
-     * @param leaves list of leaf attributes of container.
-     * @param leafLists list of leaf-list attributes of container.
-     * @throws DataModelException a violation of data model rules.
+     * @param leaves list of leaf attributes of container
+     * @param leafLists list of leaf-list attributes of container
+     * @throws DataModelException a violation of data model rules
      */
     private void validateConfig(List<YangLeaf> leaves, List<YangLeafList> leafLists) throws DataModelException {
 
-        /* If a node has "config" set to "false", no node underneath it can have
-             "config" set to "true".*/
+        /*
+         * If a node has "config" set to "false", no node underneath it can have
+         * "config" set to "true".
+         */
         if ((!isConfig) && (leaves != null)) {
             for (YangLeaf leaf : leaves) {
                 if (leaf.isConfig()) {
@@ -468,7 +476,7 @@
     /**
      * Generate the java code corresponding to YANG container.
      *
-     * @throws IOException when fails to generate the source files.
+     * @throws IOException when fails to generate the source files
      */
     @Override
     public void generateJavaCodeEntry() throws IOException {
@@ -532,4 +540,18 @@
         }
         return;
     }
+
+    @Override
+    public void detectCollidingChild(String identifierName, YangConstructType dataType) throws DataModelException {
+        // Asks helper to detect colliding child.
+        detectCollidingChildUtil(identifierName, dataType, this);
+    }
+
+    @Override
+    public void detectSelfCollision(String identifierName, YangConstructType dataType) throws DataModelException {
+        if (this.getName().equals(identifierName)) {
+            throw new DataModelException("YANG file error: Duplicate input identifier detected, same as container \""
+                    + this.getName() + "\"");
+        }
+    }
 }
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangDerivedType.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangDerivedType.java
index 31484ba..8c9628c 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangDerivedType.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangDerivedType.java
@@ -15,7 +15,7 @@
 
 import org.onosproject.yangutils.datamodel.exceptions.DataModelException;
 import org.onosproject.yangutils.parser.Parsable;
-import org.onosproject.yangutils.parser.ParsableDataType;
+import org.onosproject.yangutils.utils.YangConstructType;
 
 /*-
  * The typedef Statement
@@ -60,7 +60,7 @@
     /**
      * Get the effective YANG built-in type of the derived data type.
      *
-     * @return effective YANG built-in type of the derived data type.
+     * @return effective YANG built-in type of the derived data type
      */
     public YangDataTypes getEffectiveYangBuiltInType() {
         return effectiveYangBuiltInType;
@@ -69,7 +69,7 @@
     /**
      * Set the effective YANG built-in type of the derived data type.
      *
-     * @param builtInType effective YANG built-in type of the derived data type.
+     * @param builtInType effective YANG built-in type of the derived data type
      */
     public void setEffectiveYangBuiltInType(YangDataTypes builtInType) {
         effectiveYangBuiltInType = builtInType;
@@ -78,7 +78,7 @@
     /**
      * Get the base type information.
      *
-     * @return base type information.
+     * @return base type information
      */
     public YangType<?> getBaseType() {
         return baseType;
@@ -87,7 +87,7 @@
     /**
      * Get the base type information.
      *
-     * @param baseType base type information.
+     * @param baseType base type information
      */
     public void setBaseType(YangType<?> baseType) {
         this.baseType = baseType;
@@ -97,8 +97,8 @@
      * Get the parsable type.
      */
     @Override
-    public ParsableDataType getParsableDataType() {
-        return ParsableDataType.DERIVED;
+    public YangConstructType getYangConstructType() {
+        return YangConstructType.DERIVED;
     }
 
     /**
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangEnum.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangEnum.java
index 76ab0f3..dd79b65 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangEnum.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangEnum.java
@@ -18,7 +18,7 @@
 
 import org.onosproject.yangutils.datamodel.exceptions.DataModelException;
 import org.onosproject.yangutils.parser.Parsable;
-import org.onosproject.yangutils.parser.ParsableDataType;
+import org.onosproject.yangutils.utils.YangConstructType;
 
 import java.util.Objects;
 
@@ -73,7 +73,7 @@
     private YangStatusType status;
 
     /**
-     * value of ENUM.
+     * Value of ENUM.
      */
     private int value;
 
@@ -87,7 +87,7 @@
     /**
      * Get the named value.
      *
-     * @return the named value.
+     * @return the named value
      */
     public String getNamedValue() {
         return namedValue;
@@ -96,7 +96,7 @@
     /**
      * Set the named value.
      *
-     * @param namedValue the named value to set.
+     * @param namedValue the named value to set
      */
     public void setNamedValue(String namedValue) {
         this.namedValue = namedValue;
@@ -105,7 +105,7 @@
     /**
      * Get the description.
      *
-     * @return the description.
+     * @return the description
      */
     @Override
     public String getDescription() {
@@ -115,7 +115,7 @@
     /**
      * Set the description.
      *
-     * @param description set the description.
+     * @param description set the description
      */
     @Override
     public void setDescription(String description) {
@@ -125,7 +125,7 @@
     /**
      * Get the textual reference.
      *
-     * @return the reference.
+     * @return the reference
      */
     @Override
     public String getReference() {
@@ -135,7 +135,7 @@
     /**
      * Set the textual reference.
      *
-     * @param reference the reference to set.
+     * @param reference the reference to set
      */
     @Override
     public void setReference(String reference) {
@@ -145,7 +145,7 @@
     /**
      * Get the status.
      *
-     * @return the status.
+     * @return the status
      */
     @Override
     public YangStatusType getStatus() {
@@ -155,7 +155,7 @@
     /**
      * Set the status.
      *
-     * @param status the status to set.
+     * @param status the status to set
      */
     @Override
     public void setStatus(YangStatusType status) {
@@ -165,7 +165,7 @@
     /**
      * Get the value.
      *
-     * @return the value.
+     * @return the value
      */
     public int getValue() {
         return value;
@@ -174,7 +174,7 @@
     /**
      * Set the value.
      *
-     * @param value the value to set.
+     * @param value the value to set
      */
     public void setValue(int value) {
         this.value = value;
@@ -186,8 +186,8 @@
      * @return ParsedDataType returns ENUM_DATA
      */
     @Override
-    public ParsableDataType getParsableDataType() {
-        return ParsableDataType.ENUM_DATA;
+    public YangConstructType getYangConstructType() {
+        return YangConstructType.ENUM_DATA;
     }
 
     @Override
@@ -210,7 +210,7 @@
     /**
      * Validate the data on entering the corresponding parse tree node.
      *
-     * @throws DataModelException a violation of data model rules.
+     * @throws DataModelException a violation of data model rules
      */
     @Override
     public void validateDataOnEntry() throws DataModelException {
@@ -220,7 +220,7 @@
     /**
      * Validate the data on exiting the corresponding parse tree node.
      *
-     * @throws DataModelException a violation of data model rules.
+     * @throws DataModelException a violation of data model rules
      */
     @Override
     public void validateDataOnExit() throws DataModelException {
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangEnumeration.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangEnumeration.java
index b89cc82..25a3bbb 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangEnumeration.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangEnumeration.java
@@ -21,7 +21,7 @@
 
 import org.onosproject.yangutils.datamodel.exceptions.DataModelException;
 import org.onosproject.yangutils.parser.Parsable;
-import org.onosproject.yangutils.parser.ParsableDataType;
+import org.onosproject.yangutils.utils.YangConstructType;
 
 /*
  * The enumeration built-in type represents values from a set of
@@ -67,8 +67,8 @@
     /**
      * Add ENUM information.
      *
-     * @param enumInfo the ENUM information to be added.
-     * @throws DataModelException due to violation in data model rules.
+     * @param enumInfo the ENUM information to be added
+     * @throws DataModelException due to violation in data model rules
      */
     public void addEnumInfo(YangEnum enumInfo) throws DataModelException {
         if (!getEnumSet().add(enumInfo)) {
@@ -100,14 +100,14 @@
      * @return returns ENUMERATION_DATA
      */
     @Override
-    public ParsableDataType getParsableDataType() {
-        return ParsableDataType.ENUMERATION_DATA;
+    public YangConstructType getYangConstructType() {
+        return YangConstructType.ENUMERATION_DATA;
     }
 
     /**
      * Validate the data on entering the corresponding parse tree node.
      *
-     * @throws DataModelException a violation of data model rules.
+     * @throws DataModelException a violation of data model rules
      */
     @Override
     public void validateDataOnEntry() throws DataModelException {
@@ -117,7 +117,7 @@
     /**
      * Validate the data on exiting the corresponding parse tree node.
      *
-     * @throws DataModelException a violation of data model rules.
+     * @throws DataModelException a violation of data model rules
      */
     @Override
     public void validateDataOnExit() throws DataModelException {
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangGrouping.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangGrouping.java
index 4e3061d..9d87ee4 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangGrouping.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangGrouping.java
@@ -20,7 +20,7 @@
 
 import org.onosproject.yangutils.datamodel.exceptions.DataModelException;
 import org.onosproject.yangutils.parser.Parsable;
-import org.onosproject.yangutils.parser.ParsableDataType;
+import org.onosproject.yangutils.utils.YangConstructType;
 import org.onosproject.yangutils.translator.CachedFileHandle;
 
 /*-
@@ -110,7 +110,7 @@
     private YangStatusType status;
 
     /**
-     * package of the generated java code.
+     * Package of the generated java code.
      */
     private String pkg;
 
@@ -124,7 +124,7 @@
     /**
      * Get YANG grouping name.
      *
-     * @return YANG grouping name.
+     * @return YANG grouping name
      */
     @Override
     public String getName() {
@@ -134,7 +134,7 @@
     /**
      * Set YANG grouping name.
      *
-     * @param name YANG grouping name.
+     * @param name YANG grouping name
      */
     @Override
     public void setName(String name) {
@@ -144,7 +144,7 @@
     /**
      * Get the description.
      *
-     * @return the description.
+     * @return the description
      */
     @Override
     public String getDescription() {
@@ -154,7 +154,7 @@
     /**
      * Set the description.
      *
-     * @param description set the description.
+     * @param description set the description
      */
     @Override
     public void setDescription(String description) {
@@ -164,7 +164,7 @@
     /**
      * Get the list of leaves.
      *
-     * @return the list of leaves.
+     * @return the list of leaves
      */
     @Override
     public List<YangLeaf> getListOfLeaf() {
@@ -174,7 +174,7 @@
     /**
      * Set the list of leaves.
      *
-     * @param leafsList the list of leaf to set.
+     * @param leafsList the list of leaf to set
      */
     private void setListOfLeaf(List<YangLeaf> leafsList) {
         listOfLeaf = leafsList;
@@ -183,7 +183,7 @@
     /**
      * Add a leaf.
      *
-     * @param leaf the leaf to be added.
+     * @param leaf the leaf to be added
      */
     @Override
     public void addLeaf(YangLeaf leaf) {
@@ -197,7 +197,7 @@
     /**
      * Get the list of leaf-list.
      *
-     * @return the list of leaf-list.
+     * @return the list of leaf-list
      */
     @Override
     public List<YangLeafList> getListOfLeafList() {
@@ -207,7 +207,7 @@
     /**
      * Set the list of leaf-list.
      *
-     * @param listOfLeafList the list of leaf-list to set.
+     * @param listOfLeafList the list of leaf-list to set
      */
     private void setListOfLeafList(List<YangLeafList> listOfLeafList) {
         this.listOfLeafList = listOfLeafList;
@@ -216,7 +216,7 @@
     /**
      * Add a leaf-list.
      *
-     * @param leafList the leaf-list to be added.
+     * @param leafList the leaf-list to be added
      */
     @Override
     public void addLeafList(YangLeafList leafList) {
@@ -230,7 +230,7 @@
     /**
      * Get the textual reference.
      *
-     * @return the reference.
+     * @return the reference
      */
     @Override
     public String getReference() {
@@ -240,7 +240,7 @@
     /**
      * Set the textual reference.
      *
-     * @param reference the reference to set.
+     * @param reference the reference to set
      */
     @Override
     public void setReference(String reference) {
@@ -250,7 +250,7 @@
     /**
      * Get the status.
      *
-     * @return the status.
+     * @return the status
      */
     @Override
     public YangStatusType getStatus() {
@@ -260,7 +260,7 @@
     /**
      * Set the status.
      *
-     * @param status the status to set.
+     * @param status the status to set
      */
     @Override
     public void setStatus(YangStatusType status) {
@@ -270,17 +270,17 @@
     /**
      * Returns the type of the data.
      *
-     * @return returns GROUPING_DATA.
+     * @return returns GROUPING_DATA
      */
     @Override
-    public ParsableDataType getParsableDataType() {
-        return ParsableDataType.GROUPING_DATA;
+    public YangConstructType getYangConstructType() {
+        return YangConstructType.GROUPING_DATA;
     }
 
     /**
      * Validate the data on entering the corresponding parse tree node.
      *
-     * @throws DataModelException a violation of data model rules.
+     * @throws DataModelException a violation of data model rules
      */
     @Override
     public void validateDataOnEntry() throws DataModelException {
@@ -290,7 +290,7 @@
     /**
      * Validate the data on exiting the corresponding parse tree node.
      *
-     * @throws DataModelException a violation of data model rules.
+     * @throws DataModelException a violation of data model rules
      */
     @Override
     public void validateDataOnExit() throws DataModelException {
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangImport.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangImport.java
index 83f978e..a6e81f0 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangImport.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangImport.java
@@ -17,7 +17,7 @@
 
 import org.onosproject.yangutils.datamodel.exceptions.DataModelException;
 import org.onosproject.yangutils.parser.Parsable;
-import org.onosproject.yangutils.parser.ParsableDataType;
+import org.onosproject.yangutils.utils.YangConstructType;
 
 /*
  *  Reference:RFC 6020.
@@ -94,7 +94,7 @@
     /**
      * Get the imported module name.
      *
-     * @return the module name.
+     * @return the module name
      */
     public String getModuleName() {
         return name;
@@ -113,7 +113,7 @@
      * Get the prefix used to identify the entities from the imported module.
      *
      * @return the prefix used to identify the entities from the imported
-     *         module.
+     *         module
      */
     public String getPrefixId() {
         return prefixId;
@@ -122,7 +122,7 @@
     /**
      * Set prefix identifier.
      *
-     * @param prefixId set the prefix identifier of the imported module.
+     * @param prefixId set the prefix identifier of the imported module
      */
     public void setPrefixId(String prefixId) {
         this.prefixId = prefixId;
@@ -131,7 +131,7 @@
     /**
      * Get the revision of the imported module.
      *
-     * @return the revision of the imported module.
+     * @return the revision of the imported module
      */
     public String getRevision() {
         return revision;
@@ -140,7 +140,7 @@
     /**
      * Set the revision of the imported module.
      *
-     * @param rev set the revision of the imported module.
+     * @param rev set the revision of the imported module
      */
     public void setRevision(String rev) {
         revision = rev;
@@ -152,8 +152,8 @@
      * @return returns IMPORT_DATA
      */
     @Override
-    public ParsableDataType getParsableDataType() {
-        return ParsableDataType.IMPORT_DATA;
+    public YangConstructType getYangConstructType() {
+        return YangConstructType.IMPORT_DATA;
     }
 
     /**
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangInclude.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangInclude.java
index a506847..917a0d3 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangInclude.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangInclude.java
@@ -17,7 +17,7 @@
 
 import org.onosproject.yangutils.datamodel.exceptions.DataModelException;
 import org.onosproject.yangutils.parser.Parsable;
-import org.onosproject.yangutils.parser.ParsableDataType;
+import org.onosproject.yangutils.utils.YangConstructType;
 
 /*
  * Reference:RFC 6020.
@@ -98,8 +98,8 @@
      * @return returns INCLUDE_DATA
      */
     @Override
-    public ParsableDataType getParsableDataType() {
-        return ParsableDataType.INCLUDE_DATA;
+    public YangConstructType getYangConstructType() {
+        return YangConstructType.INCLUDE_DATA;
     }
 
     /**
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangLeaf.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangLeaf.java
index 888094e..a2e5ab5 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangLeaf.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangLeaf.java
@@ -18,7 +18,7 @@
 
 import org.onosproject.yangutils.datamodel.exceptions.DataModelException;
 import org.onosproject.yangutils.parser.Parsable;
-import org.onosproject.yangutils.parser.ParsableDataType;
+import org.onosproject.yangutils.utils.YangConstructType;
 
 /*
  * Reference:RFC 6020.
@@ -108,7 +108,7 @@
     /**
      * Get the name of leaf.
      *
-     * @return the leaf name.
+     * @return the leaf name
      */
     public String getLeafName() {
         return name;
@@ -117,7 +117,7 @@
     /**
      * Set the name of leaf.
      *
-     * @param leafName the leaf name to set.
+     * @param leafName the leaf name to set
      */
     public void setLeafName(String leafName) {
         name = leafName;
@@ -126,7 +126,7 @@
     /**
      * Get the config flag.
      *
-     * @return if config flag.
+     * @return if config flag
      */
     public Boolean isConfig() {
         return isConfig;
@@ -135,7 +135,7 @@
     /**
      * Set the config flag.
      *
-     * @param isCfg the flag value to set.
+     * @param isCfg the flag value to set
      */
     public void setConfig(boolean isCfg) {
         isConfig = isCfg;
@@ -144,7 +144,7 @@
     /**
      * Get the description.
      *
-     * @return the description.
+     * @return the description
      */
     @Override
     public String getDescription() {
@@ -154,7 +154,7 @@
     /**
      * Set the description.
      *
-     * @param description set the description.
+     * @param description set the description
      */
     @Override
     public void setDescription(String description) {
@@ -164,7 +164,7 @@
     /**
      * Get if the leaf is mandatory.
      *
-     * @return if leaf is mandatory.
+     * @return if leaf is mandatory
      */
     public boolean isMandatory() {
         return isMandatory;
@@ -182,7 +182,7 @@
     /**
      * Get the textual reference.
      *
-     * @return the reference.
+     * @return the reference
      */
     @Override
     public String getReference() {
@@ -192,7 +192,7 @@
     /**
      * Set the textual reference.
      *
-     * @param reference the reference to set.
+     * @param reference the reference to set
      */
     @Override
     public void setReference(String reference) {
@@ -202,7 +202,7 @@
     /**
      * Get the status.
      *
-     * @return the status.
+     * @return the status
      */
     @Override
     public YangStatusType getStatus() {
@@ -212,7 +212,7 @@
     /**
      * Set the status.
      *
-     * @param status the status to set.
+     * @param status the status to set
      */
     @Override
     public void setStatus(YangStatusType status) {
@@ -222,7 +222,7 @@
     /**
      * Get the units.
      *
-     * @return the units.
+     * @return the units
      */
     public String getUnits() {
         return units;
@@ -231,7 +231,7 @@
     /**
      * Set the units.
      *
-     * @param units the units to set.
+     * @param units the units to set
      */
     public void setUnits(String units) {
         this.units = units;
@@ -240,7 +240,7 @@
     /**
      * Get the data type.
      *
-     * @return the data type.
+     * @return the data type
      */
     public YangType<?> getDataType() {
         return dataType;
@@ -249,7 +249,7 @@
     /**
      * Set the data type.
      *
-     * @param dataType the data type to set.
+     * @param dataType the data type to set
      */
     public void setDataType(YangType<?> dataType) {
         this.dataType = dataType;
@@ -258,17 +258,17 @@
     /**
      * Returns the type of the parsed data.
      *
-     * @return returns LEAF_DATA.
+     * @return returns LEAF_DATA
      */
     @Override
-    public ParsableDataType getParsableDataType() {
-        return ParsableDataType.LEAF_DATA;
+    public YangConstructType getYangConstructType() {
+        return YangConstructType.LEAF_DATA;
     }
 
     /**
      * Validate the data on entering the corresponding parse tree node.
      *
-     * @throws DataModelException a violation of data model rules.
+     * @throws DataModelException a violation of data model rules
      */
     @Override
     public void validateDataOnEntry() throws DataModelException {
@@ -279,7 +279,7 @@
     /**
      * Validate the data on exiting the corresponding parse tree node.
      *
-     * @throws DataModelException a violation of data model rules.
+     * @throws DataModelException a violation of data model rules
      */
     @Override
     public void validateDataOnExit() throws DataModelException {
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangLeafList.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangLeafList.java
index 6ce3430..9852a75 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangLeafList.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangLeafList.java
@@ -18,7 +18,7 @@
 
 import org.onosproject.yangutils.datamodel.exceptions.DataModelException;
 import org.onosproject.yangutils.parser.Parsable;
-import org.onosproject.yangutils.parser.ParsableDataType;
+import org.onosproject.yangutils.utils.YangConstructType;
 
 /*
  *  Reference:RFC 6020.
@@ -130,7 +130,7 @@
     /**
      * Get the leaf-list name.
      *
-     * @return the leaf-list name.
+     * @return the leaf-list name
      */
     public String getLeafName() {
         return name;
@@ -139,7 +139,7 @@
     /**
      * Set the leaf-list name.
      *
-     * @param leafListName the leaf-list name to set.
+     * @param leafListName the leaf-list name to set
      */
     public void setLeafName(String leafListName) {
         name = leafListName;
@@ -148,7 +148,7 @@
     /**
      * Get the config flag.
      *
-     * @return the config flag.
+     * @return the config flag
      */
     public Boolean isConfig() {
         return isConfig;
@@ -157,7 +157,7 @@
     /**
      * Set the config flag.
      *
-     * @param isCfg the config flag.
+     * @param isCfg the config flag
      */
     public void setConfig(boolean isCfg) {
         isConfig = isCfg;
@@ -166,7 +166,7 @@
     /**
      * Get the description.
      *
-     * @return the description.
+     * @return the description
      */
     @Override
     public String getDescription() {
@@ -176,7 +176,7 @@
     /**
      * Set the description.
      *
-     * @param description set the description.
+     * @param description set the description
      */
     @Override
     public void setDescription(String description) {
@@ -186,7 +186,7 @@
     /**
      * Get the max elements no.
      *
-     * @return the max elements no.
+     * @return the max elements no
      */
     public int getMaxElelements() {
         return maxElelements;
@@ -195,7 +195,7 @@
     /**
      * Set the max elements no.
      *
-     * @param maxElelements max elements no.
+     * @param maxElelements max elements no
      */
     public void setMaxElelements(int maxElelements) {
         this.maxElelements = maxElelements;
@@ -204,7 +204,7 @@
     /**
      * Get the min elements no.
      *
-     * @return the min elements no.
+     * @return the min elements no
      */
     public int getMinElements() {
         return minElements;
@@ -213,7 +213,7 @@
     /**
      * Set the min elements no.
      *
-     * @param minElements the min elements no.
+     * @param minElements the min elements no
      */
     public void setMinElements(int minElements) {
         this.minElements = minElements;
@@ -222,7 +222,7 @@
     /**
      * Get the textual reference.
      *
-     * @return the reference.
+     * @return the reference
      */
     @Override
     public String getReference() {
@@ -232,7 +232,7 @@
     /**
      * Set the textual reference.
      *
-     * @param reference the reference to set.
+     * @param reference the reference to set
      */
     @Override
     public void setReference(String reference) {
@@ -242,7 +242,7 @@
     /**
      * Get the status.
      *
-     * @return the status.
+     * @return the status
      */
     @Override
     public YangStatusType getStatus() {
@@ -252,7 +252,7 @@
     /**
      * Set the status.
      *
-     * @param status the status to set.
+     * @param status the status to set
      */
     @Override
     public void setStatus(YangStatusType status) {
@@ -262,7 +262,7 @@
     /**
      * Get the units.
      *
-     * @return the units.
+     * @return the units
      */
     public String getUnits() {
         return units;
@@ -271,7 +271,7 @@
     /**
      * Set the units.
      *
-     * @param units the units to set.
+     * @param units the units to set
      */
     public void setUnits(String units) {
         this.units = units;
@@ -280,7 +280,7 @@
     /**
      * Get the data type.
      *
-     * @return the data type.
+     * @return the data type
      */
     public YangType<?> getDataType() {
         return dataType;
@@ -289,7 +289,7 @@
     /**
      * Set the data type.
      *
-     * @param dataType the data type to set.
+     * @param dataType the data type to set
      */
     public void setDataType(YangType<?> dataType) {
         this.dataType = dataType;
@@ -298,17 +298,17 @@
     /**
      * Returns the type of the parsed data.
      *
-     * @return returns LEAF_LIST_DATA.
+     * @return returns LEAF_LIST_DATA
      */
     @Override
-    public ParsableDataType getParsableDataType() {
-        return ParsableDataType.LEAF_LIST_DATA;
+    public YangConstructType getYangConstructType() {
+        return YangConstructType.LEAF_LIST_DATA;
     }
 
     /**
      * Validate the data on entering the corresponding parse tree node.
      *
-     * @throws DataModelException a violation of data model rules.
+     * @throws DataModelException a violation of data model rules
      */
     @Override
     public void validateDataOnEntry() throws DataModelException {
@@ -319,7 +319,7 @@
     /**
      * Validate the data on exiting the corresponding parse tree node.
      *
-     * @throws DataModelException a violation of data model rules.
+     * @throws DataModelException a violation of data model rules
      */
     @Override
     public void validateDataOnExit() throws DataModelException {
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangList.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangList.java
index d2ee876..c0b569b 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangList.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangList.java
@@ -16,14 +16,15 @@
 
 package org.onosproject.yangutils.datamodel;
 
+import org.onosproject.yangutils.datamodel.exceptions.DataModelException;
+import static org.onosproject.yangutils.datamodel.utils.DataModelUtils.detectCollidingChildUtil;
+import org.onosproject.yangutils.parser.Parsable;
+import org.onosproject.yangutils.translator.CachedFileHandle;
+import org.onosproject.yangutils.utils.YangConstructType;
+
 import java.util.LinkedList;
 import java.util.List;
 
-import org.onosproject.yangutils.datamodel.exceptions.DataModelException;
-import org.onosproject.yangutils.parser.Parsable;
-import org.onosproject.yangutils.parser.ParsableDataType;
-import org.onosproject.yangutils.translator.CachedFileHandle;
-
 /*-
  *  The "list" statement is used to define an interior data node in the
  *  schema tree.  A list node may exist in multiple instances in the data
@@ -67,10 +68,10 @@
  * List data represented in YANG.
  */
 public class YangList extends YangNode
-        implements YangLeavesHolder, YangCommonInfo, Parsable {
+        implements YangLeavesHolder, YangCommonInfo, Parsable, CollisionDetector {
 
     /**
-     * name of the YANG list.
+     * Name of the YANG list.
      */
     private String name;
 
@@ -177,7 +178,7 @@
     /**
      * Get the YANG list name.
      *
-     * @return YANG list name.
+     * @return YANG list name
      */
     @Override
     public String getName() {
@@ -187,7 +188,7 @@
     /**
      * Set the YANG list name.
      *
-     * @param name YANG list name.
+     * @param name YANG list name
      */
     @Override
     public void setName(String name) {
@@ -206,7 +207,7 @@
     /**
      * Set the config flag.
      *
-     * @param isCfg the config flag.
+     * @param isCfg the config flag
      */
     public void setConfig(boolean isCfg) {
         isConfig = isCfg;
@@ -215,7 +216,7 @@
     /**
      * Get the description.
      *
-     * @return the description.
+     * @return the description
      */
     @Override
     public String getDescription() {
@@ -225,7 +226,7 @@
     /**
      * Set the description.
      *
-     * @param description set the description.
+     * @param description set the description
      */
     @Override
     public void setDescription(String description) {
@@ -235,7 +236,7 @@
     /**
      * Get the list of key field names.
      *
-     * @return the list of key field names.
+     * @return the list of key field names
      */
     public List<String> getKeyList() {
         return keyList;
@@ -244,7 +245,7 @@
     /**
      * Set the list of key field names.
      *
-     * @param keyList the list of key field names.
+     * @param keyList the list of key field names
      */
     private void setKeyList(List<String> keyList) {
         this.keyList = keyList;
@@ -254,7 +255,7 @@
      * Add a key field name.
      *
      * @param key key field name.
-     * @throws DataModelException a violation of data model rules.
+     * @throws DataModelException a violation of data model rules
      */
     public void addKey(String key) throws DataModelException {
         if (getKeyList() == null) {
@@ -272,7 +273,7 @@
     /**
      * Get the list of leaves.
      *
-     * @return the list of leaves.
+     * @return the list of leaves
      */
     @Override
     public List<YangLeaf> getListOfLeaf() {
@@ -282,7 +283,7 @@
     /**
      * Set the list of leaves.
      *
-     * @param leafsList the list of leaf to set.
+     * @param leafsList the list of leaf to set
      */
     private void setListOfLeaf(List<YangLeaf> leafsList) {
         listOfLeaf = leafsList;
@@ -291,7 +292,7 @@
     /**
      * Add a leaf.
      *
-     * @param leaf the leaf to be added.
+     * @param leaf the leaf to be added
      */
     @Override
     public void addLeaf(YangLeaf leaf) {
@@ -305,7 +306,7 @@
     /**
      * Get the list of leaf-list.
      *
-     * @return the list of leaf-list.
+     * @return the list of leaf-list
      */
     @Override
     public List<YangLeafList> getListOfLeafList() {
@@ -315,7 +316,7 @@
     /**
      * Set the list of leaf-list.
      *
-     * @param listOfLeafList the list of leaf-list to set.
+     * @param listOfLeafList the list of leaf-list to set
      */
     private void setListOfLeafList(List<YangLeafList> listOfLeafList) {
         this.listOfLeafList = listOfLeafList;
@@ -324,7 +325,7 @@
     /**
      * Add a leaf-list.
      *
-     * @param leafList the leaf-list to be added.
+     * @param leafList the leaf-list to be added
      */
     @Override
     public void addLeafList(YangLeafList leafList) {
@@ -338,7 +339,7 @@
     /**
      * Get the max elements.
      *
-     * @return the max elements.
+     * @return the max elements
      */
     public int getMaxElelements() {
         return maxElelements;
@@ -347,7 +348,7 @@
     /**
      * Set the max elements.
      *
-     * @param maxElelements the max elements.
+     * @param maxElelements the max elements
      */
     public void setMaxElelements(int maxElelements) {
         this.maxElelements = maxElelements;
@@ -356,7 +357,7 @@
     /**
      * Get the minimum elements.
      *
-     * @return the minimum elements.
+     * @return the minimum elements
      */
     public int getMinElements() {
         return minElements;
@@ -365,7 +366,7 @@
     /**
      * Set the minimum elements.
      *
-     * @param minElements the minimum elements.
+     * @param minElements the minimum elements
      */
     public void setMinElements(int minElements) {
         this.minElements = minElements;
@@ -374,7 +375,7 @@
     /**
      * Get the textual reference.
      *
-     * @return the reference.
+     * @return the reference
      */
     @Override
     public String getReference() {
@@ -384,7 +385,7 @@
     /**
      * Set the textual reference.
      *
-     * @param reference the reference to set.
+     * @param reference the reference to set
      */
     @Override
     public void setReference(String reference) {
@@ -394,7 +395,7 @@
     /**
      * Get the status.
      *
-     * @return the status.
+     * @return the status
      */
     @Override
     public YangStatusType getStatus() {
@@ -404,7 +405,7 @@
     /**
      * Set the status.
      *
-     * @param status the status to set.
+     * @param status the status to set
      */
     @Override
     public void setStatus(YangStatusType status) {
@@ -414,17 +415,17 @@
     /**
      * Returns the type of the parsed data.
      *
-     * @return returns LIST_DATA.
+     * @return returns LIST_DATA
      */
     @Override
-    public ParsableDataType getParsableDataType() {
-        return ParsableDataType.LIST_DATA;
+    public YangConstructType getYangConstructType() {
+        return YangConstructType.LIST_DATA;
     }
 
     /**
      * Validate the data on entering the corresponding parse tree node.
      *
-     * @throws DataModelException a violation of data model rules.
+     * @throws DataModelException a violation of data model rules
      */
     @Override
     public void validateDataOnEntry() throws DataModelException {
@@ -434,7 +435,7 @@
     /**
      * Validate the data on exiting the corresponding parse tree node.
      *
-     * @throws DataModelException a violation of data model rules.
+     * @throws DataModelException a violation of data model rules
      */
     @Override
     public void validateDataOnExit() throws DataModelException {
@@ -464,8 +465,8 @@
      * Sets the config's value to all leaf if leaf's config statement is not
      * specified.
      *
-     * @param leaves list of leaf attributes of YANG list.
-     * @param leafLists list of leaf-list attributes of YANG list.
+     * @param leaves list of leaf attributes of YANG list
+     * @param leafLists list of leaf-list attributes of YANG list
      */
     private void setDefaultConfigValueToChild(List<YangLeaf> leaves, List<YangLeafList> leafLists) {
 
@@ -497,9 +498,9 @@
     /**
      * Validates config statement of YANG list.
      *
-     * @param leaves list of leaf attributes of YANG list.
-     * @param leafLists list of leaf-list attributes of YANG list.
-     * @throws DataModelException a violation of data model rules.
+     * @param leaves list of leaf attributes of YANG list
+     * @param leafLists list of leaf-list attributes of YANG list
+     * @throws DataModelException a violation of data model rules
      */
     private void validateConfig(List<YangLeaf> leaves, List<YangLeafList> leafLists) throws DataModelException {
 
@@ -529,9 +530,9 @@
     /**
      * Validates key statement of list.
      *
-     * @param leaves list of leaf attributes of list.
-     * @param keys list of key attributes of list.
-     * @throws DataModelException a violation of data model rules.
+     * @param leaves list of leaf attributes of list
+     * @param keys list of key attributes of list
+     * @throws DataModelException a violation of data model rules
      */
     private void validateLeafKey(List<YangLeaf> leaves, List<String> keys) throws DataModelException {
         boolean leafFound = false;
@@ -574,9 +575,9 @@
     /**
      * Validates key statement of list.
      *
-     * @param leafLists list of leaf-list attributes of list.
-     * @param keys list of key attributes of list.
-     * @throws DataModelException a violation of data model rules.
+     * @param leafLists list of leaf-list attributes of list
+     * @param keys list of key attributes of list
+     * @throws DataModelException a violation of data model rules
      */
     private void validateLeafListKey(List<YangLeafList> leafLists, List<String> keys) throws DataModelException {
         boolean leafFound = false;
@@ -668,4 +669,18 @@
         // TODO Auto-generated method stub
 
     }
+
+    @Override
+    public void detectCollidingChild(String identifierName, YangConstructType dataType) throws DataModelException {
+        // Asks helper to detect colliding child.
+        detectCollidingChildUtil(identifierName, dataType, this);
+    }
+
+    @Override
+    public void detectSelfCollision(String identifierName, YangConstructType dataType) throws DataModelException {
+        if (this.getName().equals(identifierName)) {
+            throw new DataModelException("YANG file error: Duplicate input identifier detected, same as list \"" +
+                    this.getName() + "\"");
+        }
+    }
 }
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangModule.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangModule.java
index 5644d82..e56bdab 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangModule.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangModule.java
@@ -15,20 +15,21 @@
  */
 package org.onosproject.yangutils.datamodel;
 
-import java.io.IOException;
-import java.util.LinkedList;
-import java.util.List;
-
 import org.onosproject.yangutils.datamodel.exceptions.DataModelException;
+import static org.onosproject.yangutils.datamodel.utils.DataModelUtils.detectCollidingChildUtil;
 import org.onosproject.yangutils.parser.Parsable;
-import org.onosproject.yangutils.parser.ParsableDataType;
 import org.onosproject.yangutils.translator.CachedFileHandle;
 import org.onosproject.yangutils.translator.CodeGenerator;
 import org.onosproject.yangutils.translator.GeneratedFileType;
 import org.onosproject.yangutils.translator.tojava.utils.JavaIdentifierSyntax;
 import org.onosproject.yangutils.utils.UtilConstants;
+import org.onosproject.yangutils.utils.YangConstructType;
 import org.onosproject.yangutils.utils.io.impl.FileSystemUtil;
 
+import java.io.IOException;
+import java.util.LinkedList;
+import java.util.List;
+
 /*-
  * Reference:RFC 6020.
  * The "module" statement defines the module's name,
@@ -73,7 +74,7 @@
  * Data model node to maintain information defined in YANG module.
  */
 public class YangModule extends YangNode
-        implements YangLeavesHolder, YangDesc, YangReference, Parsable, CodeGenerator {
+        implements YangLeavesHolder, YangDesc, YangReference, Parsable, CodeGenerator, CollisionDetector {
 
     /**
      * Name of the module.
@@ -588,8 +589,8 @@
      * @return returns MODULE_DATA.
      */
     @Override
-    public ParsableDataType getParsableDataType() {
-        return ParsableDataType.MODULE_DATA;
+    public YangConstructType getYangConstructType() {
+        return YangConstructType.MODULE_DATA;
     }
 
     /**
@@ -697,4 +698,15 @@
         module.addToNestedReferenceResoulutionList(node);
         return;
     }
+
+    @Override
+    public void detectCollidingChild(String identifierName, YangConstructType dataType) throws DataModelException {
+        // Asks helper to detect colliding child.
+        detectCollidingChildUtil(identifierName, dataType, this);
+    }
+
+    @Override
+    public void detectSelfCollision(String identifierName, YangConstructType dataType) throws DataModelException {
+        // Not required as module doesn't have any parent.
+    }
 }
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangMust.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangMust.java
index 63430c1..1bb9992 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangMust.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangMust.java
@@ -17,7 +17,7 @@
 
 import org.onosproject.yangutils.datamodel.exceptions.DataModelException;
 import org.onosproject.yangutils.parser.Parsable;
-import org.onosproject.yangutils.parser.ParsableDataType;
+import org.onosproject.yangutils.utils.YangConstructType;
 
 /*-
  * The "must" statement, which is optional, takes as an argument a string that
@@ -59,7 +59,7 @@
     private String description;
 
     /**
-     * reference string.
+     * Reference string.
      */
     private String reference;
 
@@ -72,7 +72,7 @@
     /**
      * Get the constraint.
      *
-     * @return the constraint.
+     * @return the constraint
      */
     public String getConstratint() {
         return constratint;
@@ -90,7 +90,7 @@
     /**
      * Get the description.
      *
-     * @return the description.
+     * @return the description
      */
     @Override
     public String getDescription() {
@@ -100,7 +100,7 @@
     /**
      * Set the description.
      *
-     * @param description set the description.
+     * @param description set the description
      */
     @Override
     public void setDescription(String description) {
@@ -110,7 +110,7 @@
     /**
      * Get the textual reference.
      *
-     * @return the reference.
+     * @return the reference
      */
     @Override
     public String getReference() {
@@ -120,7 +120,7 @@
     /**
      * Set the textual reference.
      *
-     * @param reference the reference to set.
+     * @param reference the reference to set
      */
     @Override
     public void setReference(String reference) {
@@ -133,14 +133,14 @@
      * @return returns MUST_DATA
      */
     @Override
-    public ParsableDataType getParsableDataType() {
-        return ParsableDataType.MUST_DATA;
+    public YangConstructType getYangConstructType() {
+        return YangConstructType.MUST_DATA;
     }
 
     /**
      * Validate the data on entering the corresponding parse tree node.
      *
-     * @throws DataModelException a violation of data model rules.
+     * @throws DataModelException a violation of data model rules
      */
     @Override
     public void validateDataOnEntry() throws DataModelException {
@@ -150,7 +150,7 @@
     /**
      * Validate the data on exiting the corresponding parse tree node.
      *
-     * @throws DataModelException a violation of data model rules.
+     * @throws DataModelException a violation of data model rules
      */
     @Override
     public void validateDataOnExit() throws DataModelException {
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangNameSpace.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangNameSpace.java
index 2d79a6f..897552d 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangNameSpace.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangNameSpace.java
@@ -18,7 +18,7 @@
 
 import org.onosproject.yangutils.datamodel.exceptions.DataModelException;
 import org.onosproject.yangutils.parser.Parsable;
-import org.onosproject.yangutils.parser.ParsableDataType;
+import org.onosproject.yangutils.utils.YangConstructType;
 
 /*
  *  Reference:RFC 6020.
@@ -45,7 +45,7 @@
     /**
      * Get the name space URI.
      *
-     * @return the URI.
+     * @return the URI
      */
     public String getUri() {
         return uri;
@@ -63,17 +63,17 @@
     /**
      * Returns the type of the parsed data.
      *
-     * @return returns NAMESPACE_DATA.
+     * @return returns NAMESPACE_DATA
      */
     @Override
-    public ParsableDataType getParsableDataType() {
-        return ParsableDataType.NAMESPACE_DATA;
+    public YangConstructType getYangConstructType() {
+        return YangConstructType.NAMESPACE_DATA;
     }
 
     /**
      * Validate the data on entering the corresponding parse tree node.
      *
-     * @throws DataModelException a violation of data model rules.
+     * @throws DataModelException a violation of data model rules
      */
     @Override
     public void validateDataOnEntry() throws DataModelException {
@@ -84,7 +84,7 @@
     /**
      * Validate the data on exiting the corresponding parse tree node.
      *
-     * @throws DataModelException a violation of data model rules.
+     * @throws DataModelException a violation of data model rules
      */
     @Override
     public void validateDataOnExit() throws DataModelException {
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangRevision.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangRevision.java
index 8989262..083416b 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangRevision.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangRevision.java
@@ -17,7 +17,7 @@
 
 import org.onosproject.yangutils.datamodel.exceptions.DataModelException;
 import org.onosproject.yangutils.parser.Parsable;
-import org.onosproject.yangutils.parser.ParsableDataType;
+import org.onosproject.yangutils.utils.YangConstructType;
 
 /*
  *  Reference:RFC 6020.
@@ -86,7 +86,7 @@
     /**
      * Get the description.
      *
-     * @return the description.
+     * @return the description
      */
     @Override
     public String getDescription() {
@@ -96,7 +96,7 @@
     /**
      * Set the description.
      *
-     * @param description set the description.
+     * @param description set the description
      */
     @Override
     public void setDescription(String description) {
@@ -106,7 +106,7 @@
     /**
      * Get the textual reference.
      *
-     * @return the reference.
+     * @return the reference
      */
     @Override
     public String getReference() {
@@ -116,7 +116,7 @@
     /**
      * Set the textual reference.
      *
-     * @param reference the reference to set.
+     * @param reference the reference to set
      */
     @Override
     public void setReference(String reference) {
@@ -126,17 +126,17 @@
     /**
      * Returns the type of the parsed data.
      *
-     * @return returns REVISION_DATA.
+     * @return returns REVISION_DATA
      */
     @Override
-    public ParsableDataType getParsableDataType() {
-        return ParsableDataType.REVISION_DATA;
+    public YangConstructType getYangConstructType() {
+        return YangConstructType.REVISION_DATA;
     }
 
     /**
      * Validate the data on entering the corresponding parse tree node.
      *
-     * @throws DataModelException a violation of data model rules.
+     * @throws DataModelException a violation of data model rules
      */
     @Override
     public void validateDataOnEntry() throws DataModelException {
@@ -147,7 +147,7 @@
     /**
      * Validate the data on exiting the corresponding parse tree node.
      *
-     * @throws DataModelException a violation of data model rules.
+     * @throws DataModelException a violation of data model rules
      */
     @Override
     public void validateDataOnExit() throws DataModelException {
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangSubModule.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangSubModule.java
index 467217e..f2e9119 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangSubModule.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangSubModule.java
@@ -15,14 +15,15 @@
  */
 package org.onosproject.yangutils.datamodel;
 
+import org.onosproject.yangutils.datamodel.exceptions.DataModelException;
+import static org.onosproject.yangutils.datamodel.utils.DataModelUtils.detectCollidingChildUtil;
+import org.onosproject.yangutils.parser.Parsable;
+import org.onosproject.yangutils.translator.CachedFileHandle;
+import org.onosproject.yangutils.utils.YangConstructType;
+
 import java.util.LinkedList;
 import java.util.List;
 
-import org.onosproject.yangutils.datamodel.exceptions.DataModelException;
-import org.onosproject.yangutils.parser.Parsable;
-import org.onosproject.yangutils.parser.ParsableDataType;
-import org.onosproject.yangutils.translator.CachedFileHandle;
-
 /*
  *  Reference RFC 6020.
  *
@@ -74,7 +75,7 @@
  * Data model node to maintain information defined in YANG sub-module.
  */
 public class YangSubModule extends YangNode
-        implements YangLeavesHolder, YangDesc, YangReference, Parsable {
+        implements YangLeavesHolder, YangDesc, YangReference, Parsable, CollisionDetector {
 
     /**
      * Name of sub module.
@@ -186,7 +187,7 @@
     /**
      * Set the module info.
      *
-     * @param belongsTo module info to set.
+     * @param belongsTo module info to set
      */
     public void setBelongsTo(YangBelongsTo belongsTo) {
         this.belongsTo = belongsTo;
@@ -195,7 +196,7 @@
     /**
      * Get the contact.
      *
-     * @return the contact.
+     * @return the contact
      */
     public String getContact() {
         return contact;
@@ -213,7 +214,7 @@
     /**
      * Get the description.
      *
-     * @return the description.
+     * @return the description
      */
     @Override
     public String getDescription() {
@@ -223,7 +224,7 @@
     /**
      * Set the description.
      *
-     * @param description set the description.
+     * @param description set the description
      */
     @Override
     public void setDescription(String description) {
@@ -233,7 +234,7 @@
     /**
      * Get the list of imported modules.
      *
-     * @return the list of imported modules.
+     * @return the list of imported modules
      */
     public List<YangImport> getImportList() {
         return importList;
@@ -242,7 +243,7 @@
     /**
      * prevent setting the import list from outside.
      *
-     * @param importList the import list to set.
+     * @param importList the import list to set
      */
     private void setImportList(List<YangImport> importList) {
         this.importList = importList;
@@ -251,7 +252,7 @@
     /**
      * Add the imported module information to the import list.
      *
-     * @param importedModule module being imported.
+     * @param importedModule module being imported
      */
     public void addImportedInfo(YangImport importedModule) {
 
@@ -267,7 +268,7 @@
     /**
      * Get the list of included sub modules.
      *
-     * @return the included list of sub modules.
+     * @return the included list of sub modules
      */
     public List<YangInclude> getIncludeList() {
         return includeList;
@@ -276,7 +277,7 @@
     /**
      * Set the list of included sub modules.
      *
-     * @param includeList the included list to set.
+     * @param includeList the included list to set
      */
     private void setIncludeList(List<YangInclude> includeList) {
         this.includeList = includeList;
@@ -285,7 +286,7 @@
     /**
      * Add the included sub module information to the include list.
      *
-     * @param includeModule submodule being included.
+     * @param includeModule submodule being included
      */
     public void addIncludedInfo(YangInclude includeModule) {
 
@@ -300,7 +301,7 @@
     /**
      * Get the list of leaves.
      *
-     * @return the list of leaves.
+     * @return the list of leaves
      */
     @Override
     public List<YangLeaf> getListOfLeaf() {
@@ -310,7 +311,7 @@
     /**
      * Set the list of leaves.
      *
-     * @param leafsList the list of leaf to set.
+     * @param leafsList the list of leaf to set
      */
     private void setListOfLeaf(List<YangLeaf> leafsList) {
         listOfLeaf = leafsList;
@@ -319,7 +320,7 @@
     /**
      * Add a leaf.
      *
-     * @param leaf the leaf to be added.
+     * @param leaf the leaf to be added
      */
     @Override
     public void addLeaf(YangLeaf leaf) {
@@ -333,7 +334,7 @@
     /**
      * Get the list of leaf-list.
      *
-     * @return the list of leaf-list.
+     * @return the list of leaf-list
      */
     @Override
     public List<YangLeafList> getListOfLeafList() {
@@ -343,7 +344,7 @@
     /**
      * Set the list of leaf-list.
      *
-     * @param listOfLeafList the list of leaf-list to set.
+     * @param listOfLeafList the list of leaf-list to set
      */
     private void setListOfLeafList(List<YangLeafList> listOfLeafList) {
         this.listOfLeafList = listOfLeafList;
@@ -352,7 +353,7 @@
     /**
      * Add a leaf-list.
      *
-     * @param leafList the leaf-list to be added.
+     * @param leafList the leaf-list to be added
      */
     @Override
     public void addLeafList(YangLeafList leafList) {
@@ -366,7 +367,7 @@
     /**
      * Get the sub-modules organization.
      *
-     * @return the organization.
+     * @return the organization
      */
     public String getOrganization() {
         return organization;
@@ -375,7 +376,7 @@
     /**
      * Set the sub-modules organization.
      *
-     * @param org the organization to set.
+     * @param org the organization to set
      */
     public void setOrganization(String org) {
         organization = org;
@@ -384,7 +385,7 @@
     /**
      * Get the textual reference.
      *
-     * @return the reference.
+     * @return the reference
      */
     @Override
     public String getReference() {
@@ -394,7 +395,7 @@
     /**
      * Set the textual reference.
      *
-     * @param reference the reference to set.
+     * @param reference the reference to set
      */
     @Override
     public void setReference(String reference) {
@@ -404,7 +405,7 @@
     /**
      * Get the revision.
      *
-     * @return the revision.
+     * @return the revision
      */
     public YangRevision getRevision() {
         return revision;
@@ -413,7 +414,7 @@
     /**
      * Set the revision.
      *
-     * @param revision the revision to set.
+     * @param revision the revision to set
      */
     public void setRevision(YangRevision revision) {
         this.revision = revision;
@@ -422,7 +423,7 @@
     /**
      * Get the version.
      *
-     * @return the version.
+     * @return the version
      */
     public byte getVersion() {
         return version;
@@ -431,7 +432,7 @@
     /**
      * Set the version.
      *
-     * @param version the version to set.
+     * @param version the version to set
      */
     public void setVersion(byte version) {
         this.version = version;
@@ -440,17 +441,17 @@
     /**
      * Returns the type of the parsed data.
      *
-     * @return returns SUB_MODULE_DATA.
+     * @return returns SUB_MODULE_DATA
      */
     @Override
-    public ParsableDataType getParsableDataType() {
-        return ParsableDataType.SUB_MODULE_DATA;
+    public YangConstructType getYangConstructType() {
+        return YangConstructType.SUB_MODULE_DATA;
     }
 
     /**
      * Validate the data on entering the corresponding parse tree node.
      *
-     * @throws DataModelException a violation of data model rules.
+     * @throws DataModelException a violation of data model rules
      */
     @Override
     public void validateDataOnEntry() throws DataModelException {
@@ -460,7 +461,7 @@
     /**
      * Validate the data on exiting the corresponding parse tree node.
      *
-     * @throws DataModelException a violation of data model rules.
+     * @throws DataModelException a violation of data model rules
      */
     @Override
     public void validateDataOnExit() throws DataModelException {
@@ -515,4 +516,15 @@
         // TODO Auto-generated method stub
 
     }
+
+    @Override
+    public void detectCollidingChild(String identifierName, YangConstructType dataType) throws DataModelException {
+        // Asks helper to detect colliding child.
+        detectCollidingChildUtil(identifierName, dataType, this);
+    }
+
+    @Override
+    public void detectSelfCollision(String identifierName, YangConstructType dataType) throws DataModelException {
+        // Not required as module doesn't have any parent.
+    }
 }
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangType.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangType.java
index 723319d..85db895 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangType.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangType.java
@@ -18,7 +18,7 @@
 
 import org.onosproject.yangutils.datamodel.exceptions.DataModelException;
 import org.onosproject.yangutils.parser.Parsable;
-import org.onosproject.yangutils.parser.ParsableDataType;
+import org.onosproject.yangutils.utils.YangConstructType;
 
 /*
  * Reference:RFC 6020.
@@ -77,7 +77,7 @@
     /**
      * Get the name of data type.
      *
-     * @return the name of data type.
+     * @return the name of data type
      */
     public String getDataTypeName() {
         return dataTypeName;
@@ -95,7 +95,7 @@
     /**
      * Get the type of data.
      *
-     * @return the data type.
+     * @return the data type
      */
     public YangDataTypes getDataType() {
         return dataType;
@@ -104,7 +104,7 @@
     /**
      * Set the type of data.
      *
-     * @param dataType data type.
+     * @param dataType data type
      */
     public void setDataType(YangDataTypes dataType) {
         this.dataType = dataType;
@@ -113,7 +113,7 @@
     /**
      * Get the data type meta data.
      *
-     * @return the data type meta data.
+     * @return the data type meta data
      */
     public T getDataTypeExtendedInfo() {
         return dataTypeExtendedInfo;
@@ -131,17 +131,17 @@
     /**
      * Returns the type of the parsed data.
      *
-     * @return returns TYPE_DATA.
+     * @return returns TYPE_DATA
      */
     @Override
-    public ParsableDataType getParsableDataType() {
-        return ParsableDataType.TYPE_DATA;
+    public YangConstructType getYangConstructType() {
+        return YangConstructType.TYPE_DATA;
     }
 
     /**
      * Validate the data on entering the corresponding parse tree node.
      *
-     * @throws DataModelException a violation of data model rules.
+     * @throws DataModelException a violation of data model rules
      */
     @Override
     public void validateDataOnEntry() throws DataModelException {
@@ -152,7 +152,7 @@
     /**
      * Validate the data on exiting the corresponding parse tree node.
      *
-     * @throws DataModelException a violation of data model rules.
+     * @throws DataModelException a violation of data model rules
      */
     @Override
     public void validateDataOnExit() throws DataModelException {
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangTypeDef.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangTypeDef.java
index f1250a2..a1abd8b 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangTypeDef.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangTypeDef.java
@@ -17,7 +17,7 @@
 
 import org.onosproject.yangutils.datamodel.exceptions.DataModelException;
 import org.onosproject.yangutils.parser.Parsable;
-import org.onosproject.yangutils.parser.ParsableDataType;
+import org.onosproject.yangutils.utils.YangConstructType;
 import org.onosproject.yangutils.translator.CachedFileHandle;
 
 /*-
@@ -103,7 +103,7 @@
     /**
      * Get the default value.
      *
-     * @return the default value.
+     * @return the default value
      */
     public String getDefaultValueInString() {
         return defaultValueInString;
@@ -112,7 +112,7 @@
     /**
      * Set the default value.
      *
-     * @param defaultValueInString the default value.
+     * @param defaultValueInString the default value
      */
     public void setDefaultValueInString(String defaultValueInString) {
         this.defaultValueInString = defaultValueInString;
@@ -121,7 +121,7 @@
     /**
      * Get the description.
      *
-     * @return the description.
+     * @return the description
      */
     @Override
     public String getDescription() {
@@ -131,7 +131,7 @@
     /**
      * Set the description.
      *
-     * @param description set the description.
+     * @param description set the description
      */
     @Override
     public void setDescription(String description) {
@@ -141,7 +141,7 @@
     /**
      * Get the textual reference.
      *
-     * @return the reference.
+     * @return the reference
      */
     @Override
     public String getReference() {
@@ -151,7 +151,7 @@
     /**
      * Set the textual reference.
      *
-     * @param reference the reference to set.
+     * @param reference the reference to set
      */
     @Override
     public void setReference(String reference) {
@@ -161,7 +161,7 @@
     /**
      * Get the status.
      *
-     * @return the status.
+     * @return the status
      */
     @Override
     public YangStatusType getStatus() {
@@ -171,7 +171,7 @@
     /**
      * Set the status.
      *
-     * @param status the status to set.
+     * @param status the status to set
      */
     @Override
     public void setStatus(YangStatusType status) {
@@ -181,7 +181,7 @@
     /**
      * Get the derived type.
      *
-     * @return the derived type.
+     * @return the derived type
      */
     public YangType<YangDerivedType> getDerivedType() {
         return derivedType;
@@ -190,7 +190,7 @@
     /**
      * Set the derived type.
      *
-     * @param derivedType the derived type.
+     * @param derivedType the derived type
      */
     public void setDerivedType(YangType<YangDerivedType> derivedType) {
         this.derivedType = derivedType;
@@ -220,14 +220,14 @@
      * @return returns TYPEDEF_DATA
      */
     @Override
-    public ParsableDataType getParsableDataType() {
-        return ParsableDataType.TYPEDEF_DATA;
+    public YangConstructType getYangConstructType() {
+        return YangConstructType.TYPEDEF_DATA;
     }
 
     /**
      * Validate the data on entering the corresponding parse tree node.
      *
-     * @throws DataModelException a violation of data model rules.
+     * @throws DataModelException a violation of data model rules
      */
     @Override
     public void validateDataOnEntry() throws DataModelException {
@@ -237,7 +237,7 @@
     /**
      * Validate the data on exiting the corresponding parse tree node.
      *
-     * @throws DataModelException a violation of data model rules.
+     * @throws DataModelException a violation of data model rules
      */
     @Override
     public void validateDataOnExit() throws DataModelException {
@@ -274,7 +274,7 @@
     /**
      * Get the YANG name of the typedef.
      *
-     * @return YANG name of the typedef.
+     * @return YANG name of the typedef
      */
     @Override
     public String getName() {
@@ -287,7 +287,7 @@
     /**
      * Set YANG name of the typedef.
      *
-     * @param name YANG name of the typedef.
+     * @param name YANG name of the typedef
      */
     @Override
     public void setName(String name) {
@@ -330,7 +330,7 @@
     /**
      * Set the mapped java package.
      *
-     * @param pakg mapped java package.
+     * @param pakg mapped java package
      */
     @Override
     public void setPackage(String pakg) {
@@ -341,7 +341,7 @@
     /**
      * Get the file handle of the cached file used during code generation.
      *
-     * @return cached file handle.
+     * @return cached file handle
      */
     @Override
     public CachedFileHandle getFileHandle() {
@@ -352,7 +352,7 @@
     /**
      * Set the file handle to be used used for code generation.
      *
-     * @param fileHandle cached file handle.
+     * @param fileHandle cached file handle
      */
     @Override
     public void setFileHandle(CachedFileHandle fileHandle) {
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangUses.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangUses.java
index 5326764..5e6bee4 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangUses.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangUses.java
@@ -17,7 +17,7 @@
 
 import org.onosproject.yangutils.datamodel.exceptions.DataModelException;
 import org.onosproject.yangutils.parser.Parsable;
-import org.onosproject.yangutils.parser.ParsableDataType;
+import org.onosproject.yangutils.utils.YangConstructType;
 import org.onosproject.yangutils.translator.CachedFileHandle;
 
 /*-
@@ -90,7 +90,7 @@
     /**
      * Get the name.
      *
-     * @return the name.
+     * @return the name
      */
     public String getRefGroupingName() {
         return name;
@@ -108,7 +108,7 @@
     /**
      * Get the referred group.
      *
-     * @return the referred group.
+     * @return the referred group
      */
     public YangGrouping getRefGroup() {
         return refGroup;
@@ -117,7 +117,7 @@
     /**
      * Set the referred group.
      *
-     * @param refGroup the referred group.
+     * @param refGroup the referred group
      */
     public void setRefGroup(YangGrouping refGroup) {
         this.refGroup = refGroup;
@@ -126,7 +126,7 @@
     /**
      * Get the description.
      *
-     * @return the description.
+     * @return the description
      */
     @Override
     public String getDescription() {
@@ -136,7 +136,7 @@
     /**
      * Set the description.
      *
-     * @param description set the description.
+     * @param description set the description
      */
     @Override
     public void setDescription(String description) {
@@ -146,7 +146,7 @@
     /**
      * Get the textual reference.
      *
-     * @return the reference.
+     * @return the reference
      */
     @Override
     public String getReference() {
@@ -156,7 +156,7 @@
     /**
      * Set the textual reference.
      *
-     * @param reference the reference to set.
+     * @param reference the reference to set
      */
     @Override
     public void setReference(String reference) {
@@ -166,7 +166,7 @@
     /**
      * Get the status.
      *
-     * @return the status.
+     * @return the status
      */
     @Override
     public YangStatusType getStatus() {
@@ -176,7 +176,7 @@
     /**
      * Set the status.
      *
-     * @param status the status to set.
+     * @param status the status to set
      */
     @Override
     public void setStatus(YangStatusType status) {
@@ -186,17 +186,17 @@
     /**
      * Returns the type of the data.
      *
-     * @return returns USES_DATA.
+     * @return returns USES_DATA
      */
     @Override
-    public ParsableDataType getParsableDataType() {
-        return ParsableDataType.USES_DATA;
+    public YangConstructType getYangConstructType() {
+        return YangConstructType.USES_DATA;
     }
 
     /**
      * Validate the data on entering the corresponding parse tree node.
      *
-     * @throws DataModelException a violation of data model rules.
+     * @throws DataModelException a violation of data model rules
      */
     @Override
     public void validateDataOnEntry() throws DataModelException {
@@ -206,7 +206,7 @@
     /**
      * Validate the data on exiting the corresponding parse tree node.
      *
-     * @throws DataModelException a violation of data model rules.
+     * @throws DataModelException a violation of data model rules
      */
     @Override
     public void validateDataOnExit() throws DataModelException {
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/utils/DataModelUtils.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/utils/DataModelUtils.java
new file mode 100644
index 0000000..8d94dfe
--- /dev/null
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/utils/DataModelUtils.java
@@ -0,0 +1,73 @@
+/*
+ * Copyright 2016 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.yangutils.datamodel.utils;
+
+import org.onosproject.yangutils.datamodel.CollisionDetector;
+import org.onosproject.yangutils.datamodel.YangLeaf;
+import org.onosproject.yangutils.datamodel.YangLeafList;
+import org.onosproject.yangutils.datamodel.YangLeavesHolder;
+import org.onosproject.yangutils.datamodel.YangNode;
+import org.onosproject.yangutils.datamodel.exceptions.DataModelException;
+import org.onosproject.yangutils.utils.YangConstructType;
+
+/**
+ * Utilities for data model tree.
+ */
+public final class DataModelUtils {
+
+    /**
+     * Creates a new data model tree utility.
+     */
+    private DataModelUtils() {
+    }
+
+    /**
+     * Detects the colliding identifier name in a given YANG node and its child.
+     *
+     * @param identifierName name for which collision detection is to be
+     *            checked.
+     * @param dataType type of YANG node asking for detecting collision.
+     * @param node instance of calling node.
+     * @throws DataModelException a violation of data model rules.
+     */
+    public static void detectCollidingChildUtil(String identifierName, YangConstructType dataType, YangNode node)
+            throws DataModelException {
+        if (((YangLeavesHolder) node).getListOfLeaf() != null) {
+            for (YangLeaf leaf : ((YangLeavesHolder) node).getListOfLeaf()) {
+                if (leaf.getLeafName().equals(identifierName)) {
+                    throw new DataModelException("YANG file error: Duplicate input identifier detected, same as leaf \""
+                            + leaf.getLeafName() + "\"");
+                }
+            }
+        }
+        if (((YangLeavesHolder) node).getListOfLeafList() != null) {
+            for (YangLeafList leafList : ((YangLeavesHolder) node).getListOfLeafList()) {
+                if (leafList.getLeafName().equals(identifierName)) {
+                    throw new DataModelException("YANG file error: Duplicate input identifier detected, same as leaf " +
+                            "list \"" + leafList.getLeafName() + "\"");
+                }
+            }
+        }
+        node = node.getChild();
+        while ((node != null)) {
+            if (node instanceof CollisionDetector) {
+                ((CollisionDetector) node).detectSelfCollision(identifierName, dataType);
+            }
+            node = node.getNextSibling();
+        }
+    }
+}
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/utils/package-info.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/utils/package-info.java
new file mode 100644
index 0000000..c37ed45
--- /dev/null
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/utils/package-info.java
@@ -0,0 +1,20 @@
+/*
+ * Copyright 2016 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * Utilities for checking data model tree collisions.
+ */
+package org.onosproject.yangutils.datamodel.utils;
\ No newline at end of file
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/Parsable.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/Parsable.java
index 2beae10..0d220e57 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/Parsable.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/Parsable.java
@@ -17,6 +17,7 @@
 package org.onosproject.yangutils.parser;
 
 import org.onosproject.yangutils.datamodel.exceptions.DataModelException;
+import org.onosproject.yangutils.utils.YangConstructType;
 
 /**
  * Abstraction of an entity which process the data of lexer's parse tree.
@@ -24,11 +25,11 @@
 public interface Parsable {
 
     /**
-     * Get the type of parsable data.
+     * Get the type of YANG construct data.
      *
-     * @return the type of parsable data
+     * @return the type of YANG construct data.
      */
-    ParsableDataType getParsableDataType();
+    YangConstructType getYangConstructType();
 
     /**
      * Check if the node is valid as per YANG grammar's syntax and semantics.
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/YangUtilsParser.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/YangUtilsParser.java
index 36e9c1d..2bbe70e 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/YangUtilsParser.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/YangUtilsParser.java
@@ -29,10 +29,10 @@
     /**
      * It is an entry function to initiate the YANG file parsing.
      *
-     * @param file input YANG file.
-     * @return YangNode root node of the data model tree.
-     * @throws ParserException when fails to get the data model.
-     * @throws IOException when there is an exception in IO operation.
+     * @param file input YANG file
+     * @return YangNode root node of the data model tree
+     * @throws ParserException when fails to get the data model
+     * @throws IOException when there is an exception in IO operation
      */
     YangNode getDataModel(String file) throws IOException, ParserException;
 }
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/TreeWalkListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/TreeWalkListener.java
index e2f4d70..e615d13 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/TreeWalkListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/TreeWalkListener.java
@@ -88,7 +88,7 @@
     /**
      * Returns root node.
      *
-     * @return rootNode of data model tree.
+     * @return rootNode of data model tree
      */
     public YangNode getRootNode() {
         return rootNode;
@@ -97,7 +97,7 @@
     /**
      * Set parsed data stack.
      *
-     * @param parsedDataStack stack of parsable data objects.
+     * @param parsedDataStack stack of parsable data objects
      */
     public void setParsedDataStack(Stack<Parsable> parsedDataStack) {
         this.parsedDataStack = parsedDataStack;
@@ -106,7 +106,7 @@
     /**
      * Set root node.
      *
-     * @param rootNode root node of data model tree.
+     * @param rootNode root node of data model tree
      */
     public void setRootNode(YangNode rootNode) {
         this.rootNode = rootNode;
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/BaseFileListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/BaseFileListener.java
index 527ce08..99f6807 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/BaseFileListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/BaseFileListener.java
@@ -22,14 +22,15 @@
 import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
-
-import static org.onosproject.yangutils.parser.ParsableDataType.YANGBASE_DATA;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.EXIT;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
-import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.*;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_CHILD;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_HOLDER;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.checkStackIsEmpty;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.checkStackIsNotEmpty;
+import static org.onosproject.yangutils.utils.YangConstructType.YANGBASE_DATA;
 
 /*
  * Reference: RFC6020 and YANG ANTLR Grammar
@@ -55,8 +56,8 @@
      * It is called when parser receives an input matching the grammar rule
      * (yangfile), perform validations and update the data model tree.
      *
-     * @param listener Listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener Listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processYangFileEntry(TreeWalkListener listener, GeneratedYangParser.YangfileContext ctx) {
 
@@ -69,8 +70,8 @@
      * It is called when parser exits from grammar rule (yangfile), it perform
      * validations and update the data model tree.
      *
-     * @param listener Listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener Listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processYangFileExit(TreeWalkListener listener, GeneratedYangParser.YangfileContext ctx) {
 
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/BelongsToListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/BelongsToListener.java
index fc9793f..c938190 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/BelongsToListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/BelongsToListener.java
@@ -22,13 +22,14 @@
 import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
-
-import static org.onosproject.yangutils.parser.ParsableDataType.BELONGS_TO_DATA;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.EXIT;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
-import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.*;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_CURRENT_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_HOLDER;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.checkStackIsNotEmpty;
+import static org.onosproject.yangutils.utils.YangConstructType.BELONGS_TO_DATA;
 
 /*
  * Reference: RFC6020 and YANG ANTLR Grammar
@@ -70,8 +71,8 @@
      * It is called when parser receives an input matching the grammar rule
      * (belongsto), perform validations and update the data model tree.
      *
-     * @param listener Listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener Listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processBelongsToEntry(TreeWalkListener listener,
                                              GeneratedYangParser.BelongstoStatementContext ctx) {
@@ -91,8 +92,8 @@
      * It is called when parser exits from grammar rule (belongsto), it perform
      * validations and update the data model tree.
      *
-     * @param listener Listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener Listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processBelongsToExit(TreeWalkListener listener,
                                             GeneratedYangParser.BelongstoStatementContext ctx) {
@@ -110,7 +111,7 @@
                                  ctx.IDENTIFIER().getText(), EXIT);
 
             Parsable tmpNode = listener.getParsedDataStack().peek();
-            switch (tmpNode.getParsableDataType()) {
+            switch (tmpNode.getYangConstructType()) {
             case SUB_MODULE_DATA: {
                 YangSubModule subModule = (YangSubModule) tmpNode;
                 subModule.setBelongsTo((YangBelongsTo) tmpBelongstoNode);
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/BitListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/BitListener.java
index a574091..b13b3b1 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/BitListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/BitListener.java
@@ -65,7 +65,7 @@
 import org.onosproject.yangutils.datamodel.YangBits;
 import org.onosproject.yangutils.datamodel.exceptions.DataModelException;
 import org.onosproject.yangutils.parser.Parsable;
-import static org.onosproject.yangutils.parser.ParsableDataType.BIT_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.BIT_DATA;
 import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
@@ -95,8 +95,8 @@
      * It is called when parser enters grammar rule (bit), it perform
      * validations and updates the data model tree.
      *
-     * @param listener listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processBitEntry(TreeWalkListener listener,
                                         GeneratedYangParser.BitStatementContext ctx) {
@@ -113,8 +113,8 @@
      * It is called when parser exits from grammar rule (bit), it perform
      * validations and update the data model tree.
      *
-     * @param listener Listener's object.
-     * @param ctx      context object of the grammar rule.
+     * @param listener Listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processBitExit(TreeWalkListener listener,
                                        GeneratedYangParser.BitStatementContext ctx) {
@@ -130,7 +130,7 @@
             checkStackIsNotEmpty(listener, MISSING_HOLDER, BIT_DATA, ctx.IDENTIFIER().getText(), EXIT);
 
             Parsable tmpNode = listener.getParsedDataStack().peek();
-            switch (tmpNode.getParsableDataType()) {
+            switch (tmpNode.getYangConstructType()) {
                 case BITS_DATA: {
                     YangBits yangBits = (YangBits) tmpNode;
                     if ((ctx.bitBodyStatement() == null) || (ctx.bitBodyStatement().positionStatement() == null)) {
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/BitsListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/BitsListener.java
index d8f8467..c0c302f 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/BitsListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/BitsListener.java
@@ -46,8 +46,8 @@
 import org.onosproject.yangutils.datamodel.YangLeafList;
 import org.onosproject.yangutils.datamodel.YangType;
 import org.onosproject.yangutils.parser.Parsable;
-import static org.onosproject.yangutils.parser.ParsableDataType.BITS_DATA;
-import static org.onosproject.yangutils.parser.ParsableDataType.TYPE_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.BITS_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.TYPE_DATA;
 import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
@@ -75,8 +75,8 @@
      * It is called when parser enters grammar rule (bits), it perform
      * validations and updates the data model tree.
      *
-     * @param listener listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processBitsEntry(TreeWalkListener listener,
                                                GeneratedYangParser.BitsSpecificationContext ctx) {
@@ -93,7 +93,7 @@
 
             Parsable tmpData = listener.getParsedDataStack().peek();
 
-            switch (tmpData.getParsableDataType()) {
+            switch (tmpData.getYangConstructType()) {
                 case LEAF_DATA:
                     bitsNode.setBitsName(((YangLeaf) tmpData).getLeafName());
                     break;
@@ -116,8 +116,8 @@
      * It is called when parser exits from grammar rule (bits), it perform
      * validations and update the data model tree.
      *
-     * @param listener Listener's object.
-     * @param ctx      context object of the grammar rule.
+     * @param listener Listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processBitsExit(TreeWalkListener listener,
                                               GeneratedYangParser.BitsSpecificationContext ctx) {
@@ -133,7 +133,7 @@
             checkStackIsNotEmpty(listener, MISSING_HOLDER, BITS_DATA, "", EXIT);
 
             Parsable tmpNode = listener.getParsedDataStack().peek();
-            switch (tmpNode.getParsableDataType()) {
+            switch (tmpNode.getYangConstructType()) {
                 case TYPE_DATA: {
                     YangType typeNode = (YangType) tmpNode;
                     typeNode.setDataTypeExtendedInfo((YangBits) tmpBitsNode);
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ConfigListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ConfigListener.java
index 49c0348..68d2b43 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ConfigListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ConfigListener.java
@@ -24,13 +24,12 @@
 import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
-
-import static org.onosproject.yangutils.parser.ParsableDataType.CONFIG_DATA;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_HOLDER;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_HOLDER;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.checkStackIsNotEmpty;
+import static org.onosproject.yangutils.utils.YangConstructType.CONFIG_DATA;
 
 /*
  * Reference: RFC6020 and YANG ANTLR Grammar
@@ -62,8 +61,8 @@
      * It is called when parser receives an input matching the grammar rule
      * (config), performs validation and updates the data model tree.
      *
-     * @param listener listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processConfigEntry(TreeWalkListener listener,
             GeneratedYangParser.ConfigStatementContext ctx) {
@@ -77,7 +76,7 @@
         }
 
         Parsable tmpData = listener.getParsedDataStack().peek();
-        switch (tmpData.getParsableDataType()) {
+        switch (tmpData.getYangConstructType()) {
             case LEAF_DATA:
                 YangLeaf leaf = (YangLeaf) tmpData;
                 leaf.setConfig(isConfig);
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ContactListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ContactListener.java
index 53c86cb..f1d670a 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ContactListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ContactListener.java
@@ -23,7 +23,7 @@
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
 
-import static org.onosproject.yangutils.parser.ParsableDataType.CONTACT_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.CONTACT_DATA;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_HOLDER;
@@ -86,8 +86,8 @@
      * It is called when parser receives an input matching the grammar rule
      * (contact), perform validations and update the data model tree.
      *
-     * @param listener Listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener Listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processContactEntry(TreeWalkListener listener, GeneratedYangParser.ContactStatementContext ctx) {
 
@@ -96,7 +96,7 @@
 
         // Obtain the node of the stack.
         Parsable tmpNode = listener.getParsedDataStack().peek();
-        switch (tmpNode.getParsableDataType()) {
+        switch (tmpNode.getYangConstructType()) {
         case MODULE_DATA: {
             YangModule module = (YangModule) tmpNode;
             module.setContact(ctx.string().getText());
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ContainerListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ContainerListener.java
index 2325be3..1f23449 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ContainerListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ContainerListener.java
@@ -22,24 +22,27 @@
 import org.onosproject.yangutils.datamodel.YangNode;
 import org.onosproject.yangutils.datamodel.exceptions.DataModelException;
 import org.onosproject.yangutils.parser.Parsable;
-import org.onosproject.yangutils.parser.ParsableDataType;
 import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
-import org.onosproject.yangutils.parser.impl.YangUtilsParserManager;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation;
-
-import static org.onosproject.yangutils.parser.ParsableDataType.CONTAINER_DATA;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerCollisionDetector.detectCollidingChildUtil;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.EXIT;
-import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructExtendedListenerErrorMessage;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_CURRENT_HOLDER;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_HOLDER;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.UNHANDLED_PARSED_DATA;
-import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_CARDINALITY;
-import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_CURRENT_HOLDER;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.checkStackIsNotEmpty;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.validateCardinality;
+import static org.onosproject.yangutils.utils.YangConstructType.CONFIG_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.CONTAINER_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.DESCRIPTION_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.PRESENCE_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.REFERENCE_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.STATUS_DATA;
 
 /*
  * Reference: RFC6020 and YANG ANTLR Grammar
@@ -76,8 +79,6 @@
  */
 public final class ContainerListener {
 
-    private static ParsableDataType yangConstruct;
-
     /**
      * Creates a new container listener.
      */
@@ -85,30 +86,34 @@
     }
 
     /**
-     * It is called when parser receives an input matching the grammar
-     * rule (container), performs validation and updates the data model
-     * tree.
+     * It is called when parser receives an input matching the grammar rule
+     * (container), performs validation and updates the data model tree.
      *
-     * @param listener listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processContainerEntry(TreeWalkListener listener,
-                                             GeneratedYangParser.ContainerStatementContext ctx) {
+            GeneratedYangParser.ContainerStatementContext ctx) {
 
-        YangNode parentNode;
         // Check for stack to be non empty.
         checkStackIsNotEmpty(listener, MISSING_HOLDER, CONTAINER_DATA, ctx.IDENTIFIER().getText(), ENTRY);
 
-        boolean result = validateSubStatementsCardinality(ctx);
-        if (!result) {
-            throw new ParserException(constructListenerErrorMessage(INVALID_CARDINALITY, yangConstruct, "", ENTRY));
-        }
+        // Validate sub statement cardinality.
+        validateSubStatementsCardinality(ctx);
+
+        // Check for identifier collision
+        int line = ctx.IDENTIFIER().getSymbol().getLine();
+        int charPositionInLine = ctx.IDENTIFIER().getSymbol().getCharPositionInLine();
+        String identifierName = ctx.IDENTIFIER().getText();
+        detectCollidingChildUtil(listener, line, charPositionInLine, identifierName, CONTAINER_DATA);
 
         YangContainer container = new YangContainer();
         container.setName(ctx.IDENTIFIER().getText());
 
-        /* If "config" is not specified, the default is the same as the parent
-           schema node's "config" value. */
+        /*
+         * If "config" is not specified, the default is the same as the parent
+         * schema node's "config" value.
+         */
         if (ctx.configStatement().isEmpty()) {
             boolean parentConfig = ListenerValidation.getParentNodeConfig(listener);
             container.setConfig(parentConfig);
@@ -122,7 +127,7 @@
                 curNode.addChild(container);
             } catch (DataModelException e) {
                 throw new ParserException(constructExtendedListenerErrorMessage(UNHANDLED_PARSED_DATA,
-                                CONTAINER_DATA, ctx.IDENTIFIER().getText(), ENTRY, e.getMessage()));
+                        CONTAINER_DATA, ctx.IDENTIFIER().getText(), ENTRY, e.getMessage()));
             }
             listener.getParsedDataStack().push(container);
         } else {
@@ -135,11 +140,11 @@
      * It is called when parser exits from grammar rule (container), it perform
      * validations and updates the data model tree.
      *
-     * @param listener listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processContainerExit(TreeWalkListener listener,
-                                            GeneratedYangParser.ContainerStatementContext ctx) {
+            GeneratedYangParser.ContainerStatementContext ctx) {
 
         // Check for stack to be non empty.
         checkStackIsNotEmpty(listener, MISSING_HOLDER, CONTAINER_DATA, ctx.IDENTIFIER().getText(), EXIT);
@@ -155,48 +160,22 @@
             listener.getParsedDataStack().pop();
         } else {
             throw new ParserException(constructListenerErrorMessage(MISSING_CURRENT_HOLDER, CONTAINER_DATA,
-                            ctx.IDENTIFIER().getText(), EXIT));
+                    ctx.IDENTIFIER().getText(), EXIT));
         }
     }
 
     /**
      * Validates the cardinality of container sub-statements as per grammar.
      *
-     * @param ctx context object of the grammar rule.
-     * @return true/false validation success or failure.
+     * @param ctx context object of the grammar rule
      */
-    private static boolean validateSubStatementsCardinality(GeneratedYangParser.ContainerStatementContext ctx) {
+    private static void validateSubStatementsCardinality(GeneratedYangParser.ContainerStatementContext ctx) {
 
-        if ((!ctx.presenceStatement().isEmpty())
-                && (ctx.presenceStatement().size() != YangUtilsParserManager.SUB_STATEMENT_CARDINALITY)) {
-            yangConstruct = ParsableDataType.PRESENCE_DATA;
-            return false;
-        }
-
-        if ((!ctx.configStatement().isEmpty())
-                && (ctx.configStatement().size() != YangUtilsParserManager.SUB_STATEMENT_CARDINALITY)) {
-            yangConstruct = ParsableDataType.CONFIG_DATA;
-            return false;
-        }
-
-        if ((!ctx.descriptionStatement().isEmpty())
-                && (ctx.descriptionStatement().size() != YangUtilsParserManager.SUB_STATEMENT_CARDINALITY)) {
-            yangConstruct = ParsableDataType.DESCRIPTION_DATA;
-            return false;
-        }
-
-        if ((!ctx.referenceStatement().isEmpty())
-                && (ctx.referenceStatement().size() != YangUtilsParserManager.SUB_STATEMENT_CARDINALITY)) {
-            yangConstruct = ParsableDataType.REFERENCE_DATA;
-            return false;
-        }
-
-        if ((!ctx.statusStatement().isEmpty())
-                && (ctx.statusStatement().size() != YangUtilsParserManager.SUB_STATEMENT_CARDINALITY)) {
-            yangConstruct = ParsableDataType.STATUS_DATA;
-            return false;
-        }
-
-        return true;
+        validateCardinality(ctx.presenceStatement(), PRESENCE_DATA, CONTAINER_DATA, ctx.IDENTIFIER().getText());
+        validateCardinality(ctx.configStatement(), CONFIG_DATA, CONTAINER_DATA, ctx.IDENTIFIER().getText());
+        validateCardinality(ctx.descriptionStatement(), DESCRIPTION_DATA, CONTAINER_DATA, ctx.IDENTIFIER().getText());
+        validateCardinality(ctx.referenceStatement(), REFERENCE_DATA, CONTAINER_DATA, ctx.IDENTIFIER().getText());
+        validateCardinality(ctx.statusStatement(), STATUS_DATA, CONTAINER_DATA, ctx.IDENTIFIER().getText());
+        // TODO when, grouping, typedef.
     }
 }
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/DefaultListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/DefaultListener.java
index f500cca..42b3cc4 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/DefaultListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/DefaultListener.java
@@ -45,7 +45,7 @@
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
 
-import static org.onosproject.yangutils.parser.ParsableDataType.DEFAULT_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.DEFAULT_DATA;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_HOLDER;
@@ -64,8 +64,8 @@
      * It is called when parser enters grammar rule (default), it perform
      * validations and updates the data model tree.
      *
-     * @param listener listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processDefaultEntry(TreeWalkListener listener,
             GeneratedYangParser.DefaultStatementContext ctx) {
@@ -74,7 +74,7 @@
         checkStackIsNotEmpty(listener, MISSING_HOLDER, DEFAULT_DATA, ctx.string().getText(), ENTRY);
 
         Parsable tmpNode = listener.getParsedDataStack().peek();
-        switch (tmpNode.getParsableDataType()) {
+        switch (tmpNode.getYangConstructType()) {
             case TYPEDEF_DATA: {
                 YangTypeDef typeDef = (YangTypeDef) tmpNode;
                 typeDef.setDefaultValueInString(ctx.string().getText());
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/DescriptionListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/DescriptionListener.java
index 1befa54..e27c618 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/DescriptionListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/DescriptionListener.java
@@ -22,7 +22,7 @@
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
 
-import static org.onosproject.yangutils.parser.ParsableDataType.DESCRIPTION_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.DESCRIPTION_DATA;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_HOLDER;
@@ -56,8 +56,8 @@
      * rule (description), perform validations and updates the data model
      * tree.
      *
-     * @param listener listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processDescriptionEntry(TreeWalkListener listener,
                                              GeneratedYangParser.DescriptionStatementContext ctx) {
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/EnumListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/EnumListener.java
index e255441..1d45a5e 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/EnumListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/EnumListener.java
@@ -64,7 +64,7 @@
 import org.onosproject.yangutils.datamodel.YangEnumeration;
 import org.onosproject.yangutils.datamodel.exceptions.DataModelException;
 import org.onosproject.yangutils.parser.Parsable;
-import static org.onosproject.yangutils.parser.ParsableDataType.ENUM_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.ENUM_DATA;
 import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
@@ -94,8 +94,8 @@
      * It is called when parser enters grammar rule (enum), it perform
      * validations and updates the data model tree.
      *
-     * @param listener listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processEnumEntry(TreeWalkListener listener, GeneratedYangParser.EnumStatementContext ctx) {
 
@@ -111,8 +111,8 @@
      * It is called when parser exits from grammar rule (enum), it perform
      * validations and update the data model tree.
      *
-     * @param listener Listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener Listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processEnumExit(TreeWalkListener listener, GeneratedYangParser.EnumStatementContext ctx) {
 
@@ -127,7 +127,7 @@
             checkStackIsNotEmpty(listener, MISSING_HOLDER, ENUM_DATA, ctx.string().getText(), EXIT);
 
             Parsable tmpNode = listener.getParsedDataStack().peek();
-            switch (tmpNode.getParsableDataType()) {
+            switch (tmpNode.getYangConstructType()) {
                 case ENUMERATION_DATA: {
                     YangEnumeration yangEnumeration = (YangEnumeration) tmpNode;
                     if ((ctx.enumStatementBody() == null) || (ctx.enumStatementBody().valueStatement() == null)) {
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/EnumerationListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/EnumerationListener.java
index f83c49c..5f98fa4 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/EnumerationListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/EnumerationListener.java
@@ -46,8 +46,8 @@
 import org.onosproject.yangutils.datamodel.YangLeafList;
 import org.onosproject.yangutils.datamodel.YangType;
 import org.onosproject.yangutils.parser.Parsable;
-import static org.onosproject.yangutils.parser.ParsableDataType.ENUMERATION_DATA;
-import static org.onosproject.yangutils.parser.ParsableDataType.TYPE_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.ENUMERATION_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.TYPE_DATA;
 import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
@@ -76,8 +76,8 @@
      * It is called when parser enters grammar rule (enumeration), it perform
      * validations and updates the data model tree.
      *
-     * @param listener listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processEnumerationEntry(TreeWalkListener listener,
             GeneratedYangParser.EnumSpecificationContext ctx) {
@@ -94,7 +94,7 @@
 
             Parsable tmpData = listener.getParsedDataStack().peek();
 
-            switch (tmpData.getParsableDataType()) {
+            switch (tmpData.getYangConstructType()) {
                 case LEAF_DATA:
                     enumerationNode.setEnumerationName(((YangLeaf) tmpData).getLeafName());
                     break;
@@ -117,8 +117,8 @@
      * It is called when parser exits from grammar rule (enumeration), it
      * perform validations and update the data model tree.
      *
-     * @param listener Listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener Listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processEnumerationExit(TreeWalkListener listener,
             GeneratedYangParser.EnumSpecificationContext ctx) {
@@ -134,7 +134,7 @@
             checkStackIsNotEmpty(listener, MISSING_HOLDER, ENUMERATION_DATA, "", EXIT);
 
             Parsable tmpNode = listener.getParsedDataStack().peek();
-            switch (tmpNode.getParsableDataType()) {
+            switch (tmpNode.getYangConstructType()) {
                 case TYPE_DATA: {
                     YangType typeNode = (YangType) tmpNode;
                     typeNode.setDataTypeExtendedInfo((YangEnumeration) tmpEnumerationNode);
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ImportListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ImportListener.java
index 1f5e113..bd120ad 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ImportListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ImportListener.java
@@ -23,13 +23,14 @@
 import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
-
-import static org.onosproject.yangutils.parser.ParsableDataType.IMPORT_DATA;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.EXIT;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
-import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.*;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_CURRENT_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_HOLDER;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.checkStackIsNotEmpty;
+import static org.onosproject.yangutils.utils.YangConstructType.IMPORT_DATA;
 
 /*
  * Reference: RFC6020 and YANG ANTLR Grammar
@@ -69,8 +70,8 @@
      * It is called when parser receives an input matching the grammar rule
      * (import), perform validations and update the data model tree.
      *
-     * @param listener Listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener Listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processImportEntry(TreeWalkListener listener, GeneratedYangParser.ImportStatementContext ctx) {
 
@@ -88,8 +89,8 @@
      * It is called when parser exits from grammar rule (import), it perform
      * validations and update the data model tree.
      *
-     * @param listener Listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener Listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processImportExit(TreeWalkListener listener, GeneratedYangParser.ImportStatementContext ctx) {
 
@@ -105,7 +106,7 @@
                                  EXIT);
 
             Parsable tmpNode = listener.getParsedDataStack().peek();
-            switch (tmpNode.getParsableDataType()) {
+            switch (tmpNode.getYangConstructType()) {
             case MODULE_DATA: {
                 YangModule module = (YangModule) tmpNode;
                 module.addImportedInfo((YangImport) tmpImportNode);
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/IncludeListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/IncludeListener.java
index 533db1f..6e28ada 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/IncludeListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/IncludeListener.java
@@ -23,13 +23,14 @@
 import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
-
-import static org.onosproject.yangutils.parser.ParsableDataType.INCLUDE_DATA;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.EXIT;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
-import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.*;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_CURRENT_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_HOLDER;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.checkStackIsNotEmpty;
+import static org.onosproject.yangutils.utils.YangConstructType.INCLUDE_DATA;
 
 /*
  * Reference: RFC6020 and YANG ANTLR Grammar
@@ -68,8 +69,8 @@
      * It is called when parser receives an input matching the grammar rule
      * (include), perform validations and update the data model tree.
      *
-     * @param listener Listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener Listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processIncludeEntry(TreeWalkListener listener, GeneratedYangParser.IncludeStatementContext ctx) {
 
@@ -87,8 +88,8 @@
      * It is called when parser exits from grammar rule (include), it perform
      * validations and update the data model tree.
      *
-     * @param listener Listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener Listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processIncludeExit(TreeWalkListener listener, GeneratedYangParser.IncludeStatementContext ctx) {
 
@@ -104,7 +105,7 @@
                                  EXIT);
 
             Parsable tmpNode = listener.getParsedDataStack().peek();
-            switch (tmpNode.getParsableDataType()) {
+            switch (tmpNode.getYangConstructType()) {
             case MODULE_DATA: {
                 YangModule module = (YangModule) tmpNode;
                 module.addIncludedInfo((YangInclude) tmpIncludeNode);
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/KeyListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/KeyListener.java
index 268d535..d3472aa 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/KeyListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/KeyListener.java
@@ -23,7 +23,7 @@
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
 
-import static org.onosproject.yangutils.parser.ParsableDataType.KEY_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.KEY_DATA;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructExtendedListenerErrorMessage;
@@ -59,8 +59,8 @@
      * rule (key), perform validations and updates the data model
      * tree.
      *
-     * @param listener listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processKeyEntry(TreeWalkListener listener,
                                          GeneratedYangParser.KeyStatementContext ctx) {
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/LeafListListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/LeafListListener.java
index 1ada6dd..896e8ec 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/LeafListListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/LeafListListener.java
@@ -19,21 +19,28 @@
 import org.onosproject.yangutils.datamodel.YangLeafList;
 import org.onosproject.yangutils.datamodel.YangLeavesHolder;
 import org.onosproject.yangutils.parser.Parsable;
-import org.onosproject.yangutils.parser.ParsableDataType;
 import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
-import org.onosproject.yangutils.parser.impl.YangUtilsParserManager;
-
-import static org.onosproject.yangutils.parser.ParsableDataType.LEAF_LIST_DATA;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerCollisionDetector.detectCollidingChildUtil;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.EXIT;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_HOLDER;
-import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_HOLDER;
-import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_CARDINALITY;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_CURRENT_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_HOLDER;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.checkStackIsNotEmpty;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.validateCardinality;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.validateCardinalityEqualsOne;
+import static org.onosproject.yangutils.utils.YangConstructType.CONFIG_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.DESCRIPTION_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.LEAF_LIST_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.MAX_ELEMENT_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.MIN_ELEMENT_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.REFERENCE_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.STATUS_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.TYPE_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.UNITS_DATA;
 
 /*
  * Reference: RFC6020 and YANG ANTLR Grammar
@@ -68,8 +75,6 @@
  */
 public final class LeafListListener {
 
-    private static ParsableDataType yangConstruct;
-
     /**
      * Creates a new leaf list listener.
      */
@@ -77,23 +82,26 @@
     }
 
     /**
-     * It is called when parser receives an input matching the grammar
-     * rule (leaf-list), performs validation and updates the data model
-     * tree.
+     * It is called when parser receives an input matching the grammar rule
+     * (leaf-list), performs validation and updates the data model tree.
      *
-     * @param listener listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processLeafListEntry(TreeWalkListener listener,
-                                            GeneratedYangParser.LeafListStatementContext ctx) {
+            GeneratedYangParser.LeafListStatementContext ctx) {
 
         // Check for stack to be non empty.
         checkStackIsNotEmpty(listener, MISSING_HOLDER, LEAF_LIST_DATA, ctx.IDENTIFIER().getText(), ENTRY);
 
-        boolean result = validateSubStatementsCardinality(ctx);
-        if (!result) {
-            throw new ParserException(constructListenerErrorMessage(INVALID_CARDINALITY, yangConstruct, "", ENTRY));
-        }
+        // Validate sub statement cardinality.
+        validateSubStatementsCardinality(ctx);
+
+        // Check for identifier collision
+        int line = ctx.IDENTIFIER().getSymbol().getLine();
+        int charPositionInLine = ctx.IDENTIFIER().getSymbol().getCharPositionInLine();
+        String identifierName = ctx.IDENTIFIER().getText();
+        detectCollidingChildUtil(listener, line, charPositionInLine, identifierName, LEAF_LIST_DATA);
 
         YangLeafList leafList = new YangLeafList();
         leafList.setLeafName(ctx.IDENTIFIER().getText());
@@ -106,7 +114,7 @@
             leaves.addLeafList(leafList);
         } else {
             throw new ParserException(constructListenerErrorMessage(INVALID_HOLDER, LEAF_LIST_DATA,
-                            ctx.IDENTIFIER().getText(), ENTRY));
+                    ctx.IDENTIFIER().getText(), ENTRY));
         }
         listener.getParsedDataStack().push(leafList);
     }
@@ -115,11 +123,11 @@
      * It is called when parser exits from grammar rule (leaf-list), it performs
      * validation and updates the data model tree.
      *
-     * @param listener listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processLeafListExit(TreeWalkListener listener,
-                                           GeneratedYangParser.LeafListStatementContext ctx) {
+            GeneratedYangParser.LeafListStatementContext ctx) {
 
         // Check for stack to be non empty.
         checkStackIsNotEmpty(listener, MISSING_HOLDER, LEAF_LIST_DATA, ctx.IDENTIFIER().getText(), EXIT);
@@ -136,59 +144,17 @@
      * Validates the cardinality of leaf-list sub-statements as per grammar.
      *
      * @param ctx context object of the grammar rule.
-     * @return true/false validation success or failure.
      */
-    private static boolean validateSubStatementsCardinality(GeneratedYangParser
-            .LeafListStatementContext ctx) {
+    private static void validateSubStatementsCardinality(GeneratedYangParser.LeafListStatementContext ctx) {
 
-        if (ctx.typeStatement().isEmpty()
-                || (ctx.typeStatement().size() != YangUtilsParserManager.SUB_STATEMENT_CARDINALITY)) {
-            yangConstruct = ParsableDataType.TYPE_DATA;
-            return false;
-        }
-
-        if ((!ctx.unitsStatement().isEmpty())
-                && (ctx.unitsStatement().size() != YangUtilsParserManager.SUB_STATEMENT_CARDINALITY)) {
-            yangConstruct = ParsableDataType.UNITS_DATA;
-            return false;
-        }
-
-        if ((!ctx.configStatement().isEmpty())
-                && (ctx.configStatement().size() != YangUtilsParserManager.SUB_STATEMENT_CARDINALITY)) {
-            yangConstruct = ParsableDataType.CONFIG_DATA;
-            return false;
-        }
-
-        if ((!ctx.maxElementsStatement().isEmpty())
-                && (ctx.maxElementsStatement().size() != YangUtilsParserManager.SUB_STATEMENT_CARDINALITY)) {
-            yangConstruct = ParsableDataType.MAX_ELEMENT_DATA;
-            return false;
-        }
-
-        if ((!ctx.minElementsStatement().isEmpty())
-                && (ctx.minElementsStatement().size() != YangUtilsParserManager.SUB_STATEMENT_CARDINALITY)) {
-            yangConstruct = ParsableDataType.MIN_ELEMENT_DATA;
-            return false;
-        }
-
-        if ((!ctx.descriptionStatement().isEmpty())
-                && (ctx.descriptionStatement().size() != YangUtilsParserManager.SUB_STATEMENT_CARDINALITY)) {
-            yangConstruct = ParsableDataType.DESCRIPTION_DATA;
-            return false;
-        }
-
-        if ((!ctx.referenceStatement().isEmpty())
-                && (ctx.referenceStatement().size() != YangUtilsParserManager.SUB_STATEMENT_CARDINALITY)) {
-            yangConstruct = ParsableDataType.REFERENCE_DATA;
-            return false;
-        }
-
-        if ((!ctx.statusStatement().isEmpty())
-                && (ctx.statusStatement().size() != YangUtilsParserManager.SUB_STATEMENT_CARDINALITY)) {
-            yangConstruct = ParsableDataType.STATUS_DATA;
-            return false;
-        }
-
-        return true;
+        validateCardinalityEqualsOne(ctx.typeStatement(), TYPE_DATA, LEAF_LIST_DATA, ctx.IDENTIFIER().getText());
+        validateCardinality(ctx.unitsStatement(), UNITS_DATA, LEAF_LIST_DATA, ctx.IDENTIFIER().getText());
+        validateCardinality(ctx.configStatement(), CONFIG_DATA, LEAF_LIST_DATA, ctx.IDENTIFIER().getText());
+        validateCardinality(ctx.maxElementsStatement(), MAX_ELEMENT_DATA, LEAF_LIST_DATA, ctx.IDENTIFIER().getText());
+        validateCardinality(ctx.minElementsStatement(), MIN_ELEMENT_DATA, LEAF_LIST_DATA, ctx.IDENTIFIER().getText());
+        validateCardinality(ctx.descriptionStatement(), DESCRIPTION_DATA, LEAF_LIST_DATA, ctx.IDENTIFIER().getText());
+        validateCardinality(ctx.referenceStatement(), REFERENCE_DATA, LEAF_LIST_DATA, ctx.IDENTIFIER().getText());
+        validateCardinality(ctx.statusStatement(), STATUS_DATA, LEAF_LIST_DATA, ctx.IDENTIFIER().getText());
+        //TODO ordered by
     }
-}
\ No newline at end of file
+}
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/LeafListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/LeafListener.java
index 81e9e1c..226f621 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/LeafListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/LeafListener.java
@@ -21,23 +21,29 @@
 package org.onosproject.yangutils.parser.impl.listeners;
 
 import org.onosproject.yangutils.datamodel.YangLeaf;
+import org.onosproject.yangutils.datamodel.YangLeavesHolder;
 import org.onosproject.yangutils.parser.Parsable;
-import org.onosproject.yangutils.parser.ParsableDataType;
 import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
-import org.onosproject.yangutils.datamodel.YangLeavesHolder;
-import org.onosproject.yangutils.parser.impl.YangUtilsParserManager;
-
-import static org.onosproject.yangutils.parser.ParsableDataType.LEAF_DATA;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerCollisionDetector.detectCollidingChildUtil;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.EXIT;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_HOLDER;
-import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_HOLDER;
-import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_CARDINALITY;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_CURRENT_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_HOLDER;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.checkStackIsNotEmpty;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.validateCardinality;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.validateCardinalityEqualsOne;
+import static org.onosproject.yangutils.utils.YangConstructType.CONFIG_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.DESCRIPTION_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.LEAF_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.MANDATORY_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.REFERENCE_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.STATUS_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.TYPE_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.UNITS_DATA;
 
 /*
  * Reference: RFC6020 and YANG ANTLR Grammar
@@ -66,13 +72,11 @@
  */
 
 /**
- * Implements listener based call back function corresponding to the "leaf"
- * rule defined in ANTLR grammar file for corresponding ABNF rule in RFC 6020.
+ * Implements listener based call back function corresponding to the "leaf" rule
+ * defined in ANTLR grammar file for corresponding ABNF rule in RFC 6020.
  */
 public final class LeafListener {
 
-    private static ParsableDataType yangConstruct;
-
     /**
      * Creates a new leaf listener.
      */
@@ -80,23 +84,26 @@
     }
 
     /**
-     * It is called when parser receives an input matching the grammar
-     * rule (leaf), performs validation and updates the data model
-     * tree.
+     * It is called when parser receives an input matching the grammar rule
+     * (leaf), performs validation and updates the data model tree.
      *
-     * @param listener listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processLeafEntry(TreeWalkListener listener,
-                                        GeneratedYangParser.LeafStatementContext ctx) {
+            GeneratedYangParser.LeafStatementContext ctx) {
 
         // Check for stack to be non empty.
         checkStackIsNotEmpty(listener, MISSING_HOLDER, LEAF_DATA, ctx.IDENTIFIER().getText(), ENTRY);
 
-        boolean result = validateSubStatementsCardinality(ctx);
-        if (!result) {
-            throw new ParserException(constructListenerErrorMessage(INVALID_CARDINALITY, yangConstruct, "", ENTRY));
-        }
+        // Validate sub statement cardinality.
+        validateSubStatementsCardinality(ctx);
+
+        // Check for identifier collision
+        int line = ctx.IDENTIFIER().getSymbol().getLine();
+        int charPositionInLine = ctx.IDENTIFIER().getSymbol().getCharPositionInLine();
+        String identifierName = ctx.IDENTIFIER().getText();
+        detectCollidingChildUtil(listener, line, charPositionInLine, identifierName, LEAF_DATA);
 
         YangLeaf leaf = new YangLeaf();
         leaf.setLeafName(ctx.IDENTIFIER().getText());
@@ -123,7 +130,7 @@
      * @param ctx context object of the grammar rule.
      */
     public static void processLeafExit(TreeWalkListener listener,
-                                       GeneratedYangParser.LeafStatementContext ctx) {
+            GeneratedYangParser.LeafStatementContext ctx) {
 
         // Check for stack to be non empty.
         checkStackIsNotEmpty(listener, MISSING_HOLDER, LEAF_DATA, ctx.IDENTIFIER().getText(), EXIT);
@@ -132,7 +139,7 @@
             listener.getParsedDataStack().pop();
         } else {
             throw new ParserException(constructListenerErrorMessage(MISSING_CURRENT_HOLDER, LEAF_DATA,
-                            ctx.IDENTIFIER().getText(), EXIT));
+                    ctx.IDENTIFIER().getText(), EXIT));
         }
     }
 
@@ -140,53 +147,16 @@
      * Validates the cardinality of leaf sub-statements as per grammar.
      *
      * @param ctx context object of the grammar rule.
-     * @return true/false validation success or failure.
      */
-    private static boolean validateSubStatementsCardinality(GeneratedYangParser
-            .LeafStatementContext ctx) {
+    private static void validateSubStatementsCardinality(GeneratedYangParser.LeafStatementContext ctx) {
 
-        if (ctx.typeStatement().isEmpty()
-                || (ctx.typeStatement().size() != YangUtilsParserManager.SUB_STATEMENT_CARDINALITY)) {
-            yangConstruct = ParsableDataType.TYPE_DATA;
-            return false;
-        }
-
-        if ((!ctx.unitsStatement().isEmpty())
-                && (ctx.unitsStatement().size() != YangUtilsParserManager.SUB_STATEMENT_CARDINALITY)) {
-            yangConstruct = ParsableDataType.UNITS_DATA;
-            return false;
-        }
-
-        if ((!ctx.configStatement().isEmpty())
-                && (ctx.configStatement().size() != YangUtilsParserManager.SUB_STATEMENT_CARDINALITY)) {
-            yangConstruct = ParsableDataType.CONFIG_DATA;
-            return false;
-        }
-
-        if ((!ctx.mandatoryStatement().isEmpty())
-                && (ctx.mandatoryStatement().size() != YangUtilsParserManager.SUB_STATEMENT_CARDINALITY)) {
-            yangConstruct = ParsableDataType.MANDATORY_DATA;
-            return false;
-        }
-
-        if ((!ctx.descriptionStatement().isEmpty())
-                && (ctx.descriptionStatement().size() != YangUtilsParserManager.SUB_STATEMENT_CARDINALITY)) {
-            yangConstruct = ParsableDataType.DESCRIPTION_DATA;
-            return false;
-        }
-
-        if ((!ctx.referenceStatement().isEmpty())
-                && (ctx.referenceStatement().size() != YangUtilsParserManager.SUB_STATEMENT_CARDINALITY)) {
-            yangConstruct = ParsableDataType.REFERENCE_DATA;
-            return false;
-        }
-
-        if ((!ctx.statusStatement().isEmpty())
-                && (ctx.statusStatement().size() != YangUtilsParserManager.SUB_STATEMENT_CARDINALITY)) {
-            yangConstruct = ParsableDataType.STATUS_DATA;
-            return false;
-        }
-
-        return true;
+        validateCardinalityEqualsOne(ctx.typeStatement(), TYPE_DATA, LEAF_DATA, ctx.IDENTIFIER().getText());
+        validateCardinality(ctx.unitsStatement(), UNITS_DATA, LEAF_DATA, ctx.IDENTIFIER().getText());
+        validateCardinality(ctx.configStatement(), CONFIG_DATA, LEAF_DATA, ctx.IDENTIFIER().getText());
+        validateCardinality(ctx.mandatoryStatement(), MANDATORY_DATA, LEAF_DATA, ctx.IDENTIFIER().getText());
+        validateCardinality(ctx.descriptionStatement(), DESCRIPTION_DATA, LEAF_DATA, ctx.IDENTIFIER().getText());
+        validateCardinality(ctx.referenceStatement(), REFERENCE_DATA, LEAF_DATA, ctx.IDENTIFIER().getText());
+        validateCardinality(ctx.statusStatement(), STATUS_DATA, LEAF_DATA, ctx.IDENTIFIER().getText());
+        //TODO when.
     }
-}
\ No newline at end of file
+}
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ListListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ListListener.java
index 2319b8e..7692025 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ListListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ListListener.java
@@ -16,31 +16,38 @@
 
 package org.onosproject.yangutils.parser.impl.listeners;
 
-import org.onosproject.yangutils.datamodel.YangList;
 import org.onosproject.yangutils.datamodel.YangContainer;
+import org.onosproject.yangutils.datamodel.YangList;
 import org.onosproject.yangutils.datamodel.YangModule;
 import org.onosproject.yangutils.datamodel.YangNode;
 import org.onosproject.yangutils.datamodel.YangNodeType;
 import org.onosproject.yangutils.datamodel.exceptions.DataModelException;
 import org.onosproject.yangutils.parser.Parsable;
-import org.onosproject.yangutils.parser.ParsableDataType;
 import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
-import org.onosproject.yangutils.parser.impl.YangUtilsParserManager;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation;
-
-import static org.onosproject.yangutils.parser.ParsableDataType.LIST_DATA;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerCollisionDetector.detectCollidingChildUtil;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.EXIT;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructExtendedListenerErrorMessage;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_HOLDER;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_CURRENT_HOLDER;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_HOLDER;
-import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_HOLDER;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.UNHANDLED_PARSED_DATA;
-import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_CARDINALITY;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.checkStackIsNotEmpty;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.validateCardinality;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.validateCardinalityNonNull;
+import static org.onosproject.yangutils.utils.YangConstructType.CONFIG_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.DATA_DEF_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.DESCRIPTION_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.KEY_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.LIST_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.MAX_ELEMENT_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.MIN_ELEMENT_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.REFERENCE_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.STATUS_DATA;
 
 /*
  * Reference: RFC6020 and YANG ANTLR Grammar
@@ -74,13 +81,11 @@
  */
 
 /**
- * Implements listener based call back function corresponding to the "list"
- * rule defined in ANTLR grammar file for corresponding ABNF rule in RFC 6020.
+ * Implements listener based call back function corresponding to the "list" rule
+ * defined in ANTLR grammar file for corresponding ABNF rule in RFC 6020.
  */
 public final class ListListener {
 
-    private static ParsableDataType yangConstruct;
-
     /**
      * Creates a new list listener.
      */
@@ -88,30 +93,35 @@
     }
 
     /**
-     * It is called when parser receives an input matching the grammar
-     * rule (list), performs validation and updates the data model
-     * tree.
+     * It is called when parser receives an input matching the grammar rule
+     * (list), performs validation and updates the data model tree.
      *
-     * @param listener listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processListEntry(TreeWalkListener listener,
-                                             GeneratedYangParser.ListStatementContext ctx) {
+            GeneratedYangParser.ListStatementContext ctx) {
 
         YangNode curNode;
 
         checkStackIsNotEmpty(listener, MISSING_HOLDER, LIST_DATA, ctx.IDENTIFIER().getText(), ENTRY);
 
-        boolean result = validateSubStatementsCardinality(ctx);
-        if (!result) {
-            throw new ParserException(constructListenerErrorMessage(INVALID_CARDINALITY, yangConstruct, "", ENTRY));
-        }
+        // Validate sub statement cardinality.
+        validateSubStatementsCardinality(ctx);
+
+        // Check for identifier collision
+        int line = ctx.IDENTIFIER().getSymbol().getLine();
+        int charPositionInLine = ctx.IDENTIFIER().getSymbol().getCharPositionInLine();
+        String identifierName = ctx.IDENTIFIER().getText();
+        detectCollidingChildUtil(listener, line, charPositionInLine, identifierName, LIST_DATA);
 
         YangList yangList = new YangList(YangNodeType.LIST_NODE);
         yangList.setName(ctx.IDENTIFIER().getText());
 
-        /* If "config" is not specified, the default is the same as the parent
-           schema node's "config" value. */
+        /*
+         * If "config" is not specified, the default is the same as the parent
+         * schema node's "config" value.
+         */
         if (ctx.configStatement().isEmpty()) {
             boolean parentConfig = ListenerValidation.getParentNodeConfig(listener);
             yangList.setConfig(parentConfig);
@@ -130,7 +140,7 @@
             listener.getParsedDataStack().push(yangList);
         } else {
             throw new ParserException(constructListenerErrorMessage(INVALID_HOLDER, LIST_DATA,
-                            ctx.IDENTIFIER().getText(), ENTRY));
+                    ctx.IDENTIFIER().getText(), ENTRY));
         }
     }
 
@@ -138,11 +148,11 @@
      * It is called when parser exits from grammar rule (list), it performs
      * validation and updates the data model tree.
      *
-     * @param listener listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processListExit(TreeWalkListener listener,
-                                            GeneratedYangParser.ListStatementContext ctx) {
+            GeneratedYangParser.ListStatementContext ctx) {
 
         checkStackIsNotEmpty(listener, MISSING_HOLDER, LIST_DATA, ctx.IDENTIFIER().getText(), EXIT);
 
@@ -157,65 +167,25 @@
             listener.getParsedDataStack().pop();
         } else {
             throw new ParserException(constructListenerErrorMessage(MISSING_CURRENT_HOLDER, LIST_DATA,
-                            ctx.IDENTIFIER().getText(), EXIT));
+                    ctx.IDENTIFIER().getText(), EXIT));
         }
     }
 
     /**
      * Validates the cardinality of list sub-statements as per grammar.
      *
-     * @param ctx context object of the grammar rule.
-     * @return true/false validation success or failure.
+     * @param ctx context object of the grammar rule
      */
-    private static boolean validateSubStatementsCardinality(GeneratedYangParser.ListStatementContext ctx) {
+    private static void validateSubStatementsCardinality(GeneratedYangParser.ListStatementContext ctx) {
 
-        if ((!ctx.keyStatement().isEmpty())
-                && (ctx.keyStatement().size() != YangUtilsParserManager.SUB_STATEMENT_CARDINALITY)) {
-            yangConstruct = ParsableDataType.KEY_DATA;
-            return false;
-        }
-
-        if ((!ctx.configStatement().isEmpty())
-                && (ctx.configStatement().size() != YangUtilsParserManager.SUB_STATEMENT_CARDINALITY)) {
-            yangConstruct = ParsableDataType.CONFIG_DATA;
-            return false;
-        }
-
-        if ((!ctx.maxElementsStatement().isEmpty())
-                && (ctx.maxElementsStatement().size() != YangUtilsParserManager.SUB_STATEMENT_CARDINALITY)) {
-            yangConstruct = ParsableDataType.MAX_ELEMENT_DATA;
-            return false;
-        }
-
-        if ((!ctx.minElementsStatement().isEmpty())
-                && (ctx.minElementsStatement().size() != YangUtilsParserManager.SUB_STATEMENT_CARDINALITY)) {
-            yangConstruct = ParsableDataType.MIN_ELEMENT_DATA;
-            return false;
-        }
-
-        if ((!ctx.descriptionStatement().isEmpty())
-                && (ctx.descriptionStatement().size() != YangUtilsParserManager.SUB_STATEMENT_CARDINALITY)) {
-            yangConstruct = ParsableDataType.DESCRIPTION_DATA;
-            return false;
-        }
-
-        if ((!ctx.referenceStatement().isEmpty())
-                && (ctx.referenceStatement().size() != YangUtilsParserManager.SUB_STATEMENT_CARDINALITY)) {
-            yangConstruct = ParsableDataType.REFERENCE_DATA;
-            return false;
-        }
-
-        if ((!ctx.statusStatement().isEmpty())
-                && (ctx.statusStatement().size() != YangUtilsParserManager.SUB_STATEMENT_CARDINALITY)) {
-            yangConstruct = ParsableDataType.STATUS_DATA;
-            return false;
-        }
-
-        if (ctx.dataDefStatement().isEmpty()) {
-            yangConstruct = ParsableDataType.LIST_DATA;
-            return false;
-        }
-
-        return true;
+        validateCardinality(ctx.keyStatement(), KEY_DATA, LIST_DATA, ctx.IDENTIFIER().getText());
+        validateCardinality(ctx.configStatement(), CONFIG_DATA, LIST_DATA, ctx.IDENTIFIER().getText());
+        validateCardinality(ctx.maxElementsStatement(), MAX_ELEMENT_DATA, LIST_DATA, ctx.IDENTIFIER().getText());
+        validateCardinality(ctx.minElementsStatement(), MIN_ELEMENT_DATA, LIST_DATA, ctx.IDENTIFIER().getText());
+        validateCardinality(ctx.descriptionStatement(), DESCRIPTION_DATA, LIST_DATA, ctx.IDENTIFIER().getText());
+        validateCardinality(ctx.referenceStatement(), REFERENCE_DATA, LIST_DATA, ctx.IDENTIFIER().getText());
+        validateCardinality(ctx.statusStatement(), STATUS_DATA, LIST_DATA, ctx.IDENTIFIER().getText());
+        validateCardinalityNonNull(ctx.dataDefStatement(), DATA_DEF_DATA, LIST_DATA, ctx.IDENTIFIER().getText());
+        //TODO when, typedef, grouping, unique
     }
-}
\ No newline at end of file
+}
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/MandatoryListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/MandatoryListener.java
index 2e118ce..ea33cd7 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/MandatoryListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/MandatoryListener.java
@@ -22,7 +22,7 @@
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
 
-import static org.onosproject.yangutils.parser.ParsableDataType.MANDATORY_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.MANDATORY_DATA;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_HOLDER;
@@ -62,8 +62,8 @@
      * rule (mandatory), performs validation and updates the data model
      * tree.
      *
-     * @param listener listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processMandatoryEntry(TreeWalkListener listener,
                                           GeneratedYangParser.MandatoryStatementContext ctx) {
@@ -72,7 +72,7 @@
         checkStackIsNotEmpty(listener, MISSING_HOLDER, MANDATORY_DATA, "", ENTRY);
 
         Parsable tmpNode = listener.getParsedDataStack().peek();
-        switch (tmpNode.getParsableDataType()) {
+        switch (tmpNode.getYangConstructType()) {
             case LEAF_DATA:
                 YangLeaf leaf = (YangLeaf) tmpNode;
                 if (ctx.TRUE_KEYWORD() != null) {
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/MaxElementsListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/MaxElementsListener.java
index bf59311..72ba44d 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/MaxElementsListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/MaxElementsListener.java
@@ -23,7 +23,7 @@
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
 
-import static org.onosproject.yangutils.parser.ParsableDataType.MAX_ELEMENT_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.MAX_ELEMENT_DATA;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_HOLDER;
@@ -60,8 +60,8 @@
      * rule (max-elements), performs validation and updates the data model
      * tree.
      *
-     * @param listener listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processMaxElementsEntry(TreeWalkListener listener,
                                              GeneratedYangParser.MaxElementsStatementContext ctx) {
@@ -77,7 +77,7 @@
         }
 
         Parsable tmpData = listener.getParsedDataStack().peek();
-        switch (tmpData.getParsableDataType()) {
+        switch (tmpData.getYangConstructType()) {
             case LEAF_LIST_DATA:
                 YangLeafList leafList = (YangLeafList) tmpData;
                 leafList.setMaxElelements(maxElementsValue);
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/MinElementsListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/MinElementsListener.java
index 8e1e2f7..a89c6ce 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/MinElementsListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/MinElementsListener.java
@@ -23,7 +23,7 @@
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
 
-import static org.onosproject.yangutils.parser.ParsableDataType.MIN_ELEMENT_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.MIN_ELEMENT_DATA;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_HOLDER;
@@ -61,8 +61,8 @@
      * rule (min-elements), performs validation and updates the data model
      * tree.
      *
-     * @param listener listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processMinElementsEntry(TreeWalkListener listener,
                                                GeneratedYangParser.MinElementsStatementContext ctx) {
@@ -71,7 +71,7 @@
         checkStackIsNotEmpty(listener, MISSING_HOLDER, MIN_ELEMENT_DATA, ctx.INTEGER().getText(), ENTRY);
 
         Parsable tmpData = listener.getParsedDataStack().peek();
-        switch (tmpData.getParsableDataType()) {
+        switch (tmpData.getYangConstructType()) {
             case LEAF_LIST_DATA:
                 YangLeafList leafList = (YangLeafList) tmpData;
                 leafList.setMinElements(Integer.parseInt(ctx.INTEGER().getText()));
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ModuleListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ModuleListener.java
index 8e808a2..f4f6ef5 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ModuleListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ModuleListener.java
@@ -20,14 +20,15 @@
 import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
-
-import static org.onosproject.yangutils.parser.ParsableDataType.MODULE_DATA;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.EXIT;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
-import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.*;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_CURRENT_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_HOLDER;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.checkStackIsEmpty;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.checkStackIsNotEmpty;
+import static org.onosproject.yangutils.utils.YangConstructType.MODULE_DATA;
 
 /*
  * Reference: RFC6020 and YANG ANTLR Grammar
@@ -63,8 +64,8 @@
      * It is called when parser receives an input matching the grammar rule
      * (module), perform validations and update the data model tree.
      *
-     * @param listener Listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener Listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processModuleEntry(TreeWalkListener listener, GeneratedYangParser.ModuleStatementContext ctx) {
 
@@ -74,6 +75,10 @@
         YangModule yangModule = new YangModule();
         yangModule.setName(ctx.IDENTIFIER().getText());
 
+        if (ctx.moduleBody(0).moduleHeaderStatement().yangVersionStatement() == null) {
+            yangModule.setVersion((byte) 1);
+        }
+
         listener.getParsedDataStack().push(yangModule);
     }
 
@@ -81,8 +86,8 @@
      * It is called when parser exits from grammar rule (module), it perform
      * validations and update the data model tree.
      *
-     * @param listener Listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener Listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processModuleExit(TreeWalkListener listener, GeneratedYangParser.ModuleStatementContext ctx) {
 
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/NamespaceListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/NamespaceListener.java
index 4030ada..a2cf36c 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/NamespaceListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/NamespaceListener.java
@@ -25,7 +25,7 @@
 
 import java.net.URI;
 
-import static org.onosproject.yangutils.parser.ParsableDataType.NAMESPACE_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.NAMESPACE_DATA;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_HOLDER;
@@ -70,8 +70,8 @@
      * It is called when parser receives an input matching the grammar rule
      * (namespace), perform validations and update the data model tree.
      *
-     * @param listener Listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener Listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processNamespaceEntry(TreeWalkListener listener,
                                              GeneratedYangParser.NamespaceStatementContext ctx) {
@@ -80,7 +80,7 @@
         checkStackIsNotEmpty(listener, MISSING_HOLDER, NAMESPACE_DATA, ctx.string().getText(), ENTRY);
 
         if (!validateUriValue(ctx.string().getText())) {
-            ParserException parserException = new ParserException("Invalid namespace URI");
+            ParserException parserException = new ParserException("YANG file error: Invalid namespace URI");
             parserException.setLine(ctx.string().STRING(0).getSymbol().getLine());
             parserException.setCharPosition(ctx.string().STRING(0).getSymbol().getCharPositionInLine());
             throw parserException;
@@ -88,7 +88,7 @@
 
         // Obtain the node of the stack.
         Parsable tmpNode = listener.getParsedDataStack().peek();
-        switch (tmpNode.getParsableDataType()) {
+        switch (tmpNode.getYangConstructType()) {
         case MODULE_DATA: {
             YangModule module = (YangModule) tmpNode;
             YangNameSpace uri = new YangNameSpace();
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/OrganizationListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/OrganizationListener.java
index ab8681c..d0525c0 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/OrganizationListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/OrganizationListener.java
@@ -23,7 +23,7 @@
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
 
-import static org.onosproject.yangutils.parser.ParsableDataType.ORGANIZATION_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.ORGANIZATION_DATA;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_HOLDER;
@@ -88,8 +88,8 @@
      * It is called when parser receives an input matching the grammar rule
      * (organization), perform validations and update the data model tree.
      *
-     * @param listener Listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener Listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processOrganizationEntry(TreeWalkListener listener,
                                                 GeneratedYangParser.OrganizationStatementContext ctx) {
@@ -100,7 +100,7 @@
 
         // Obtain the node of the stack.
         Parsable tmpNode = listener.getParsedDataStack().peek();
-        switch (tmpNode.getParsableDataType()) {
+        switch (tmpNode.getYangConstructType()) {
         case MODULE_DATA: {
             YangModule module = (YangModule) tmpNode;
             module.setOrganization(ctx.string().getText());
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/PositionListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/PositionListener.java
index 92b3e68..41835d6 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/PositionListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/PositionListener.java
@@ -36,7 +36,7 @@
 import org.onosproject.yangutils.datamodel.YangBit;
 import org.onosproject.yangutils.datamodel.YangBits;
 import org.onosproject.yangutils.parser.Parsable;
-import static org.onosproject.yangutils.parser.ParsableDataType.POSITION_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.POSITION_DATA;
 import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
@@ -65,8 +65,8 @@
      * It is called when parser receives an input matching the grammar rule
      * (position), perform validations and update the data model tree.
      *
-     * @param listener Listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener Listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processPositionEntry(TreeWalkListener listener,
                                             GeneratedYangParser.PositionStatementContext ctx) {
@@ -76,7 +76,7 @@
 
         // Obtain the node of the stack.
         Parsable tmpNode = listener.getParsedDataStack().peek();
-        switch (tmpNode.getParsableDataType()) {
+        switch (tmpNode.getYangConstructType()) {
             case BIT_DATA: {
                 YangBit bitNode = (YangBit) tmpNode;
                 if (!isBitPositionValid(listener, ctx)) {
@@ -97,8 +97,8 @@
     /**
      * Validates BITS position value correctness and uniqueness.
      *
-     * @param listener Listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener Listener's object
+     * @param ctx context object of the grammar rule
      * @return validation result
      */
     private static boolean isBitPositionValid(TreeWalkListener listener,
@@ -109,18 +109,18 @@
         checkStackIsNotEmpty(listener, MISSING_HOLDER, POSITION_DATA, ctx.INTEGER().getText(), ENTRY);
 
         if (Integer.valueOf(ctx.INTEGER().getText()) < 0) {
-            errMsg = "Negative value of position is invalid";
+            errMsg = "YANG file error: Negative value of position is invalid.";
             listener.getParsedDataStack().push(bitNode);
             return false;
         }
 
         Parsable tmpNode = listener.getParsedDataStack().peek();
-        switch (tmpNode.getParsableDataType()) {
+        switch (tmpNode.getYangConstructType()) {
             case BITS_DATA: {
                 YangBits yangBits = (YangBits) tmpNode;
                 for (YangBit curBit : yangBits.getBitSet()) {
                     if (Integer.valueOf(ctx.INTEGER().getText()) == curBit.getPosition()) {
-                        errMsg = "Duplicate value of position is invalid";
+                        errMsg = "YANG file error: Duplicate value of position is invalid.";
                         listener.getParsedDataStack().push(bitNode);
                         return false;
                     }
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/PrefixListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/PrefixListener.java
index 6b6db62..e59cda0 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/PrefixListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/PrefixListener.java
@@ -24,7 +24,7 @@
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
 
-import static org.onosproject.yangutils.parser.ParsableDataType.PREFIX_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.PREFIX_DATA;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_HOLDER;
@@ -70,8 +70,8 @@
      * It is called when parser receives an input matching the grammar rule
      * (prefix),perform validations and update the data model tree.
      *
-     * @param listener Listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener Listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processPrefixEntry(TreeWalkListener listener, GeneratedYangParser.PrefixStatementContext ctx) {
 
@@ -80,7 +80,7 @@
 
         // Obtain the node of the stack.
         Parsable tmpNode = listener.getParsedDataStack().peek();
-        switch (tmpNode.getParsableDataType()) {
+        switch (tmpNode.getYangConstructType()) {
         case MODULE_DATA: {
             YangModule module = (YangModule) tmpNode;
             module.setPrefix(ctx.IDENTIFIER().getText());
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/PresenceListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/PresenceListener.java
index a771307..74e40b1 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/PresenceListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/PresenceListener.java
@@ -22,8 +22,8 @@
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
 
-import static org.onosproject.yangutils.parser.ParsableDataType.PRESENCE_DATA;
-import static org.onosproject.yangutils.parser.ParsableDataType.CONTAINER_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.PRESENCE_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.CONTAINER_DATA;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_HOLDER;
@@ -57,8 +57,8 @@
      * rule (presence), performs validation and updates the data model
      * tree.
      *
-     * @param listener listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processPresenceEntry(TreeWalkListener listener,
                                              GeneratedYangParser.PresenceStatementContext ctx) {
@@ -67,7 +67,7 @@
         checkStackIsNotEmpty(listener, MISSING_HOLDER, PRESENCE_DATA, ctx.string().getText(), ENTRY);
 
         Parsable tmpData = listener.getParsedDataStack().peek();
-        if (tmpData.getParsableDataType() == CONTAINER_DATA) {
+        if (tmpData.getYangConstructType() == CONTAINER_DATA) {
             YangContainer container = (YangContainer) tmpData;
             container.setPresence(ctx.string().getText());
         } else {
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ReferenceListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ReferenceListener.java
index 6e83e86..aaca80c 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ReferenceListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ReferenceListener.java
@@ -22,7 +22,7 @@
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
 
-import static org.onosproject.yangutils.parser.ParsableDataType.REFERENCE_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.REFERENCE_DATA;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_HOLDER;
@@ -56,8 +56,8 @@
      * rule (reference), performs validation and updates the data model
      * tree.
      *
-     * @param listener listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processReferenceEntry(TreeWalkListener listener,
                                              GeneratedYangParser.ReferenceStatementContext ctx) {
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/RevisionDateListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/RevisionDateListener.java
index bef6f8e3..17fe6b7 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/RevisionDateListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/RevisionDateListener.java
@@ -27,7 +27,7 @@
 import java.text.SimpleDateFormat;
 import java.util.Date;
 
-import static org.onosproject.yangutils.parser.ParsableDataType.REVISION_DATE_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.REVISION_DATE_DATA;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_HOLDER;
@@ -79,8 +79,8 @@
      * It is called when parser receives an input matching the grammar rule
      * (revision date),perform validations and update the data model tree.
      *
-     * @param listener Listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener Listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processRevisionDateEntry(TreeWalkListener listener,
                                                 GeneratedYangParser.RevisionDateStatementContext ctx) {
@@ -90,7 +90,7 @@
                              ENTRY);
 
         if (!isDateValid(ctx.DATE_ARG().getText())) {
-            ParserException parserException = new ParserException("Input date is not correct");
+            ParserException parserException = new ParserException("YANG file error: Input date is not correct");
             parserException.setLine(ctx.DATE_ARG().getSymbol().getLine());
             parserException.setCharPosition(ctx.DATE_ARG().getSymbol().getCharPositionInLine());
             throw parserException;
@@ -98,7 +98,7 @@
 
         // Obtain the node of the stack.
         Parsable tmpNode = listener.getParsedDataStack().peek();
-        switch (tmpNode.getParsableDataType()) {
+        switch (tmpNode.getYangConstructType()) {
         case IMPORT_DATA: {
             YangImport importNode = (YangImport) tmpNode;
             importNode.setRevision(ctx.DATE_ARG().getText());
@@ -118,8 +118,8 @@
     /**
      * Validates the revision date.
      *
-     * @param dateToValidate input revision date.
-     * @return validation result, true for success, false for failure.
+     * @param dateToValidate input revision date
+     * @return validation result, true for success, false for failure
      */
     private static boolean isDateValid(String dateToValidate) {
 
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/RevisionListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/RevisionListener.java
index a135891..32675cd 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/RevisionListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/RevisionListener.java
@@ -24,13 +24,19 @@
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
 
-import static org.onosproject.yangutils.parser.ParsableDataType.REVISION_DATA;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_CURRENT_HOLDER;
+import static org.onosproject.yangutils.utils.YangConstructType.REVISION_DATA;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.EXIT;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
-import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.*;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.checkStackIsNotEmpty;
 
+import java.text.ParseException;
+import java.text.SimpleDateFormat;
+import java.util.Date;
+
 /*
  * Reference: RFC6020 and YANG ANTLR Grammar
  *
@@ -75,8 +81,8 @@
      * It is called when parser receives an input matching the grammar rule
      * (revision),perform validations and update the data model tree.
      *
-     * @param listener Listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener Listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processRevisionEntry(TreeWalkListener listener,
                                             GeneratedYangParser.RevisionStatementContext ctx) {
@@ -91,6 +97,13 @@
             // TODO to be implemented.
         }
 
+        if (!isDateValid(ctx.DATE_ARG().getText())) {
+            ParserException parserException = new ParserException("YANG file error: Input date is not correct");
+            parserException.setLine(ctx.DATE_ARG().getSymbol().getLine());
+            parserException.setCharPosition(ctx.DATE_ARG().getSymbol().getCharPositionInLine());
+            throw parserException;
+        }
+
         YangRevision revisionNode = new YangRevision();
         revisionNode.setRevDate(ctx.DATE_ARG().getText());
 
@@ -101,8 +114,8 @@
      * It is called when parser exits from grammar rule (revision), it perform
      * validations and update the data model tree.
      *
-     * @param listener Listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener Listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processRevisionExit(TreeWalkListener listener, GeneratedYangParser.RevisionStatementContext
             ctx) {
@@ -119,7 +132,7 @@
                                  EXIT);
 
             Parsable tmpNode = listener.getParsedDataStack().peek();
-            switch (tmpNode.getParsableDataType()) {
+            switch (tmpNode.getYangConstructType()) {
             case MODULE_DATA: {
                 YangModule module = (YangModule) tmpNode;
                 module.setRevision((YangRevision) tmpRevisionNode);
@@ -144,8 +157,8 @@
     /**
      * Validate revision.
      *
-     * @param listener Listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener Listener's object
+     * @param ctx context object of the grammar rule
      * @return validation result
      */
     private static boolean validateRevision(TreeWalkListener listener,
@@ -153,4 +166,29 @@
         // TODO to be implemented
         return true;
     }
+
+    /**
+     * Validates the revision date.
+     *
+     * @param dateToValidate input revision date
+     * @return validation result, true for success, false for failure
+     */
+    private static boolean isDateValid(String dateToValidate) {
+
+        if (dateToValidate == null) {
+            return false;
+        }
+
+        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
+        sdf.setLenient(false);
+
+        try {
+            //if not valid, it will throw ParseException
+            Date date = sdf.parse(dateToValidate);
+            System.out.println(date);
+        } catch (ParseException e) {
+            return false;
+        }
+        return true;
+    }
 }
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/StatusListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/StatusListener.java
index 82cdabd..379994e 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/StatusListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/StatusListener.java
@@ -23,7 +23,7 @@
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
 
-import static org.onosproject.yangutils.parser.ParsableDataType.STATUS_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.STATUS_DATA;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_HOLDER;
@@ -62,8 +62,8 @@
      * rule (status), performs validation and updates the data model
      * tree.
      *
-     * @param listener listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processStatusEntry(TreeWalkListener listener,
                                           GeneratedYangParser.StatusStatementContext ctx) {
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/SubModuleListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/SubModuleListener.java
index b577bcf..4f8a64e 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/SubModuleListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/SubModuleListener.java
@@ -20,14 +20,15 @@
 import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
-
-import static org.onosproject.yangutils.parser.ParsableDataType.SUB_MODULE_DATA;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.EXIT;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
-import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.*;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_CURRENT_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_HOLDER;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.checkStackIsEmpty;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.checkStackIsNotEmpty;
+import static org.onosproject.yangutils.utils.YangConstructType.SUB_MODULE_DATA;
 
 /*
  * Reference: RFC6020 and YANG ANTLR Grammar
@@ -64,8 +65,8 @@
      * It is called when parser receives an input matching the grammar rule (sub
      * module), perform validations and update the data model tree.
      *
-     * @param listener Listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener Listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processSubModuleEntry(TreeWalkListener listener,
                                              GeneratedYangParser.SubModuleStatementContext ctx) {
@@ -77,6 +78,10 @@
         YangSubModule yangSubModule = new YangSubModule();
         yangSubModule.setName(ctx.IDENTIFIER().getText());
 
+        if (ctx.submoduleBody(0).submoduleHeaderStatement().yangVersionStatement() == null) {
+            yangSubModule.setVersion((byte) 1);
+        }
+
         listener.getParsedDataStack().push(yangSubModule);
     }
 
@@ -84,8 +89,8 @@
      * It is called when parser exits from grammar rule (submodule), it perform
      * validations and update the data model tree.
      *
-     * @param listener Listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener Listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processSubModuleExit(TreeWalkListener listener,
                                             GeneratedYangParser.SubModuleStatementContext ctx) {
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/TypeDefListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/TypeDefListener.java
index 5373232..5ba9780 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/TypeDefListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/TypeDefListener.java
@@ -58,24 +58,23 @@
 import org.onosproject.yangutils.datamodel.YangTypeDef;
 import org.onosproject.yangutils.datamodel.exceptions.DataModelException;
 import org.onosproject.yangutils.parser.Parsable;
-import org.onosproject.yangutils.parser.ParsableDataType;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.validateCardinality;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.validateCardinalityEqualsOne;
 import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
-import org.onosproject.yangutils.parser.impl.YangUtilsParserManager;
 
-import static org.onosproject.yangutils.parser.ParsableDataType.DEFAULT_DATA;
-import static org.onosproject.yangutils.parser.ParsableDataType.DESCRIPTION_DATA;
-import static org.onosproject.yangutils.parser.ParsableDataType.REFERENCE_DATA;
-import static org.onosproject.yangutils.parser.ParsableDataType.STATUS_DATA;
-import static org.onosproject.yangutils.parser.ParsableDataType.TYPEDEF_DATA;
-import static org.onosproject.yangutils.parser.ParsableDataType.TYPE_DATA;
-import static org.onosproject.yangutils.parser.ParsableDataType.UNITS_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.DEFAULT_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.DESCRIPTION_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.REFERENCE_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.STATUS_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.TYPEDEF_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.TYPE_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.UNITS_DATA;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.EXIT;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructExtendedListenerErrorMessage;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
-import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_CARDINALITY;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_HOLDER;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_CURRENT_HOLDER;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_HOLDER;
@@ -88,8 +87,6 @@
  */
 public final class TypeDefListener {
 
-    private static ParsableDataType yangConstruct;
-
     /**
      * Creates a new typedef listener.
      */
@@ -100,8 +97,8 @@
      * It is called when parser enters grammar rule (typedef), it perform
      * validations and updates the data model tree.
      *
-     * @param listener listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processTypeDefEntry(TreeWalkListener listener,
             GeneratedYangParser.TypedefStatementContext ctx) {
@@ -109,10 +106,8 @@
         // Check for stack to be non empty.
         checkStackIsNotEmpty(listener, MISSING_HOLDER, TYPEDEF_DATA, ctx.IDENTIFIER().getText(), ENTRY);
 
-        boolean result = validateSubStatementsCardinality(ctx);
-        if (!result) {
-            throw new ParserException(constructListenerErrorMessage(INVALID_CARDINALITY, yangConstruct, "", ENTRY));
-        }
+        // Validate sub statement cardinality.
+        validateSubStatementsCardinality(ctx);
 
         /*
          * Create a derived type information, the base type must be set in type
@@ -150,8 +145,8 @@
      * It is called when parser exits from grammar rule (typedef), it perform
      * validations and updates the data model tree.
      *
-     * @param listener listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processTypeDefExit(TreeWalkListener listener,
             GeneratedYangParser.TypedefStatementContext ctx) {
@@ -178,45 +173,15 @@
     /**
      * Validates the cardinality of typedef sub-statements as per grammar.
      *
-     * @param ctx context object of the grammar rule.
-     * @return true/false validation success or failure.
+     * @param ctx context object of the grammar rule
      */
-    private static boolean validateSubStatementsCardinality(GeneratedYangParser.TypedefStatementContext ctx) {
+    private static void validateSubStatementsCardinality(GeneratedYangParser.TypedefStatementContext ctx) {
 
-        if ((!ctx.unitsStatement().isEmpty())
-                && (ctx.unitsStatement().size() != YangUtilsParserManager.SUB_STATEMENT_CARDINALITY)) {
-            yangConstruct = UNITS_DATA;
-            return false;
-        }
-
-        if ((!ctx.defaultStatement().isEmpty())
-                && (ctx.defaultStatement().size() != YangUtilsParserManager.SUB_STATEMENT_CARDINALITY)) {
-            yangConstruct = DEFAULT_DATA;
-            return false;
-        }
-
-        if (ctx.typeStatement().size() != YangUtilsParserManager.SUB_STATEMENT_CARDINALITY) {
-            yangConstruct = TYPE_DATA;
-            return false;
-        }
-
-        if ((!ctx.descriptionStatement().isEmpty())
-                && (ctx.descriptionStatement().size() != YangUtilsParserManager.SUB_STATEMENT_CARDINALITY)) {
-            yangConstruct = DESCRIPTION_DATA;
-            return false;
-        }
-
-        if ((!ctx.referenceStatement().isEmpty())
-                && (ctx.referenceStatement().size() != YangUtilsParserManager.SUB_STATEMENT_CARDINALITY)) {
-            yangConstruct = REFERENCE_DATA;
-            return false;
-        }
-
-        if ((!ctx.statusStatement().isEmpty())
-                && (ctx.statusStatement().size() != YangUtilsParserManager.SUB_STATEMENT_CARDINALITY)) {
-            yangConstruct = STATUS_DATA;
-            return false;
-        }
-        return true;
+        validateCardinality(ctx.unitsStatement(), UNITS_DATA, TYPEDEF_DATA, ctx.IDENTIFIER().getText());
+        validateCardinality(ctx.defaultStatement(), DEFAULT_DATA, TYPEDEF_DATA, ctx.IDENTIFIER().getText());
+        validateCardinalityEqualsOne(ctx.typeStatement(), TYPE_DATA, TYPEDEF_DATA, ctx.IDENTIFIER().getText());
+        validateCardinality(ctx.descriptionStatement(), DESCRIPTION_DATA, TYPEDEF_DATA, ctx.IDENTIFIER().getText());
+        validateCardinality(ctx.referenceStatement(), REFERENCE_DATA, TYPEDEF_DATA, ctx.IDENTIFIER().getText());
+        validateCardinality(ctx.statusStatement(), STATUS_DATA, TYPEDEF_DATA, ctx.IDENTIFIER().getText());
     }
 }
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/TypeListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/TypeListener.java
index 891a982..18a7aef 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/TypeListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/TypeListener.java
@@ -27,7 +27,7 @@
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
 
-import static org.onosproject.yangutils.parser.ParsableDataType.TYPE_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.TYPE_DATA;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.EXIT;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
@@ -66,8 +66,8 @@
      * It is called when parser receives an input matching the grammar rule
      * (type), performs validation and updates the data model tree.
      *
-     * @param listener listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processTypeEntry(TreeWalkListener listener,
             GeneratedYangParser.TypeStatementContext ctx) {
@@ -88,8 +88,8 @@
      * It is called when parser exits from grammar rule (type), it perform
      * validations and update the data model tree.
      *
-     * @param listener Listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener Listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processTypeExit(TreeWalkListener listener,
             GeneratedYangParser.TypeStatementContext ctx) {
@@ -107,7 +107,7 @@
         checkStackIsNotEmpty(listener, MISSING_HOLDER, TYPE_DATA, ctx.string().getText(), EXIT);
 
         Parsable tmpData = listener.getParsedDataStack().peek();
-        switch (tmpData.getParsableDataType()) {
+        switch (tmpData.getYangConstructType()) {
             case LEAF_DATA:
                 YangLeaf leaf = (YangLeaf) tmpData;
                 leaf.setDataType((YangType) type);
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/UnitsListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/UnitsListener.java
index 6a83aaa..623b244 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/UnitsListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/UnitsListener.java
@@ -23,7 +23,7 @@
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
 
-import static org.onosproject.yangutils.parser.ParsableDataType.UNITS_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.UNITS_DATA;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_HOLDER;
@@ -57,8 +57,8 @@
      * rule (units), performs validation and updates the data model
      * tree.
      *
-     * @param listener listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processUnitsEntry(TreeWalkListener listener,
                                            GeneratedYangParser.UnitsStatementContext ctx) {
@@ -67,7 +67,7 @@
         checkStackIsNotEmpty(listener, MISSING_HOLDER, UNITS_DATA, ctx.string().getText(), ENTRY);
 
         Parsable tmpData = listener.getParsedDataStack().peek();
-        switch (tmpData.getParsableDataType()) {
+        switch (tmpData.getYangConstructType()) {
             case LEAF_DATA:
                 YangLeaf leaf = (YangLeaf) tmpData;
                 leaf.setUnits(ctx.string().getText());
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ValueListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ValueListener.java
index 7c050dc..80cf8a7 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ValueListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ValueListener.java
@@ -29,7 +29,7 @@
 import org.onosproject.yangutils.datamodel.YangEnum;
 import org.onosproject.yangutils.datamodel.YangEnumeration;
 import org.onosproject.yangutils.parser.Parsable;
-import static org.onosproject.yangutils.parser.ParsableDataType.VALUE_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.VALUE_DATA;
 import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
@@ -55,8 +55,8 @@
      * It is called when parser receives an input matching the grammar rule
      * (value), perform validations and update the data model tree.
      *
-     * @param listener Listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener Listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processValueEntry(TreeWalkListener listener, GeneratedYangParser.ValueStatementContext ctx) {
 
@@ -65,7 +65,7 @@
 
         // Obtain the node of the stack.
         Parsable tmpNode = listener.getParsedDataStack().peek();
-        switch (tmpNode.getParsableDataType()) {
+        switch (tmpNode.getYangConstructType()) {
             case ENUM_DATA: {
                 YangEnum enumNode = (YangEnum) tmpNode;
                 if (!isEnumValueValid(listener, ctx)) {
@@ -86,8 +86,8 @@
     /**
      * Validates ENUM value uniqueness.
      *
-     * @param listener Listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener Listener's object
+     * @param ctx context object of the grammar rule
      * @return validation result
      */
     private static boolean isEnumValueValid(TreeWalkListener listener, GeneratedYangParser.ValueStatementContext ctx) {
@@ -97,7 +97,7 @@
         checkStackIsNotEmpty(listener, MISSING_HOLDER, VALUE_DATA, ctx.INTEGER().getText(), ENTRY);
 
         Parsable tmpNode = listener.getParsedDataStack().peek();
-        switch (tmpNode.getParsableDataType()) {
+        switch (tmpNode.getYangConstructType()) {
             case ENUMERATION_DATA: {
                 YangEnumeration yangEnumeration = (YangEnumeration) tmpNode;
                 for (YangEnum curEnum : yangEnumeration.getEnumSet()) {
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/VersionListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/VersionListener.java
index 021ae0d..9b9a388 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/VersionListener.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/VersionListener.java
@@ -23,7 +23,7 @@
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
 
-import static org.onosproject.yangutils.parser.ParsableDataType.VERSION_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.VERSION_DATA;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_HOLDER;
@@ -78,8 +78,8 @@
      * It is called when parser receives an input matching the grammar rule
      * (version), perform validations and update the data model tree.
      *
-     * @param listener Listener's object.
-     * @param ctx context object of the grammar rule.
+     * @param listener Listener's object
+     * @param ctx context object of the grammar rule
      */
     public static void processVersionEntry(TreeWalkListener listener,
                                            GeneratedYangParser.YangVersionStatementContext ctx) {
@@ -89,7 +89,7 @@
 
         Integer version = Integer.valueOf(ctx.INTEGER().getText());
         if (!isVersionValid(version)) {
-            ParserException parserException = new ParserException("Input version not supported");
+            ParserException parserException = new ParserException("YANG file error: Input version not supported");
             parserException.setLine(ctx.INTEGER().getSymbol().getLine());
             parserException.setCharPosition(ctx.INTEGER().getSymbol().getCharPositionInLine());
             throw parserException;
@@ -97,7 +97,7 @@
 
         // Obtain the node of the stack.
         Parsable tmpNode = listener.getParsedDataStack().peek();
-        switch (tmpNode.getParsableDataType()) {
+        switch (tmpNode.getYangConstructType()) {
         case MODULE_DATA: {
             YangModule module = (YangModule) tmpNode;
             module.setVersion((byte) 1);
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/parserutils/ListenerCollisionDetector.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/parserutils/ListenerCollisionDetector.java
new file mode 100644
index 0000000..7697e6a
--- /dev/null
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/parserutils/ListenerCollisionDetector.java
@@ -0,0 +1,72 @@
+/*
+ * Copyright 2016 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.yangutils.parser.impl.parserutils;
+
+import org.onosproject.yangutils.datamodel.CollisionDetector;
+import org.onosproject.yangutils.datamodel.exceptions.DataModelException;
+import org.onosproject.yangutils.parser.exceptions.ParserException;
+import org.onosproject.yangutils.parser.impl.TreeWalkListener;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.EXIT;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.INVALID_HOLDER;
+import org.onosproject.yangutils.utils.YangConstructType;
+
+/**
+ * Check the YANG construct collision in a YANG file.
+ */
+public final class ListenerCollisionDetector {
+
+    /**
+     * Creates a new listener collision.
+     */
+    private ListenerCollisionDetector() {
+    }
+
+    /**
+     * Detects that the identifiers of all these child nodes must be unique
+     * within all cases in a choice.
+     *
+     * @param listener listener's object
+     * @param line line of identifier in YANG file, required for error
+     *            reporting
+     * @param charPosition character position of identifier in YANG file,
+     *            required for error reporting
+     * @param identifierName name for which uniqueness is to be detected
+     * @param constructType type of YANG construct for which collision check is
+     *            to be performed
+     * @throws ParserException if identifier is not unique
+     */
+    public static void detectCollidingChildUtil(TreeWalkListener listener, int line, int charPosition,
+            String identifierName, YangConstructType constructType)
+                    throws ParserException {
+
+        if (listener.getParsedDataStack().peek() instanceof CollisionDetector) {
+            try {
+                ((CollisionDetector) listener.getParsedDataStack().peek()).detectCollidingChild(
+                        identifierName, constructType);
+            } catch (DataModelException e) {
+                ParserException parserException = new ParserException(e.getMessage());
+                parserException.setLine(line);
+                parserException.setCharPosition(charPosition);
+                throw parserException;
+            }
+        } else {
+            throw new ParserException(constructListenerErrorMessage(INVALID_HOLDER, constructType, identifierName,
+                    EXIT));
+        }
+    }
+}
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/parserutils/ListenerErrorLocation.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/parserutils/ListenerErrorLocation.java
index 4c3efd6..ee47115 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/parserutils/ListenerErrorLocation.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/parserutils/ListenerErrorLocation.java
@@ -33,8 +33,8 @@
     /**
      * Returns the message corresponding to listener error location.
      *
-     * @param errorLocation enum value for type of error.
-     * @return message corresponding to listener error location.
+     * @param errorLocation enum value for type of error
+     * @return message corresponding to listener error location
      */
     public static String getErrorLocationMessage(ListenerErrorLocation errorLocation) {
 
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/parserutils/ListenerErrorMessageConstruction.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/parserutils/ListenerErrorMessageConstruction.java
index 1ef25e3..538cb0e 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/parserutils/ListenerErrorMessageConstruction.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/parserutils/ListenerErrorMessageConstruction.java
@@ -16,9 +16,9 @@
 
 package org.onosproject.yangutils.parser.impl.parserutils;
 
-import org.onosproject.yangutils.parser.ParsableDataType;
+import org.onosproject.yangutils.utils.YangConstructType;
 
-import static org.onosproject.yangutils.parser.ParsableDataType.getParsableDataType;
+import static org.onosproject.yangutils.utils.YangConstructType.getYangConstructType;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.getErrorLocationMessage;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.getErrorType;
 
@@ -37,21 +37,21 @@
      * Constructs message for error with extended information and returns the
      * same.
      *
-     * @param errorType error type needs to be set in error message.
-     * @param parsableDataType type of parsable data in which error occurred.
+     * @param errorType error type needs to be set in error message
+     * @param yangConstructType type of parsable data in which error occurred
      * @param parsableDataTypeName identifier/string of parsable data type in
-     *            which error occurred.
-     * @param errorLocation location where error occurred.
-     * @param extendedErrorInformation extended error information.
-     * @return constructed error message.
+     *            which error occurred
+     * @param errorLocation location where error occurred
+     * @param extendedErrorInformation extended error information
+     * @return constructed error message
      */
     public static String constructExtendedListenerErrorMessage(ListenerErrorType errorType,
-                                                               ParsableDataType parsableDataType,
+                                                               YangConstructType yangConstructType,
                                                                String parsableDataTypeName,
                                                                ListenerErrorLocation errorLocation,
                                                                String extendedErrorInformation) {
         String newErrorMessage;
-        newErrorMessage = constructListenerErrorMessage(errorType, parsableDataType, parsableDataTypeName,
+        newErrorMessage = constructListenerErrorMessage(errorType, yangConstructType, parsableDataTypeName,
                                                         errorLocation)
                 + "\n"
                 + "Error Information: "
@@ -63,22 +63,22 @@
      * Constructs message for error during listener based tree walk and returns
      * the same.
      *
-     * @param errorType error type needs to be set in error message.
-     * @param parsableDataType type of parsable data in which error occurred.
+     * @param errorType error type needs to be set in error message
+     * @param yangConstructType type of parsable data in which error occurred
      * @param parsableDataTypeName identifier/string of parsable data type in
-     *            which error occurred.
-     * @param errorLocation location where error occurred.
-     * @return constructed error message.
+     *            which error occurred
+     * @param errorLocation location where error occurred
+     * @return constructed error message
      */
     public static String constructListenerErrorMessage(ListenerErrorType errorType,
-                                                       ParsableDataType parsableDataType,
+                                                       YangConstructType yangConstructType,
                                                        String parsableDataTypeName,
                                                        ListenerErrorLocation errorLocation) {
 
         String errorMessage;
 
         errorMessage = "Internal parser error detected: " + getErrorType(errorType) + " "
-                + getParsableDataType(parsableDataType);
+                + getYangConstructType(yangConstructType);
 
         if (!parsableDataTypeName.isEmpty()) {
             errorMessage = errorMessage + " \"" + parsableDataTypeName + "\" ";
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/parserutils/ListenerErrorType.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/parserutils/ListenerErrorType.java
index 1d061d7..32620d5 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/parserutils/ListenerErrorType.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/parserutils/ListenerErrorType.java
@@ -60,6 +60,11 @@
     INVALID_CONTENT(),
 
     /**
+     * Represents that the identifier collision is detected.
+     */
+    IDENTIFIER_COLLISION(),
+
+    /**
      * Represents that some of earlier parsed data is not handled correctly.
      */
     UNHANDLED_PARSED_DATA();
@@ -67,8 +72,8 @@
     /**
      * Returns the message corresponding to listener error type.
      *
-     * @param errorType enum value for type of error.
-     * @return message corresponding to listener error type.
+     * @param errorType enum value for type of error
+     * @return message corresponding to listener error type
      */
     public static String getErrorType(ListenerErrorType errorType) {
 
@@ -87,6 +92,8 @@
                 return "Duplicate";
             case INVALID_CONTENT:
                 return "Invalid content in";
+            case IDENTIFIER_COLLISION:
+                return "Identifier collision detected for";
             case UNHANDLED_PARSED_DATA:
                 return "Unhandled parsed data at";
             default:
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/parserutils/ListenerValidation.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/parserutils/ListenerValidation.java
index 26e4907..d460634 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/parserutils/ListenerValidation.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/parserutils/ListenerValidation.java
@@ -20,10 +20,13 @@
 import org.onosproject.yangutils.datamodel.YangList;
 import org.onosproject.yangutils.datamodel.YangNode;
 import org.onosproject.yangutils.parser.Parsable;
-import org.onosproject.yangutils.parser.ParsableDataType;
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
+import org.onosproject.yangutils.utils.YangConstructType;
+import static org.onosproject.yangutils.utils.YangConstructType.getYangConstructType;
+
+import java.util.List;
 
 /**
  * It's a utility to carry out listener validation.
@@ -39,15 +42,15 @@
     /**
      * Checks parsed data stack is not empty.
      *
-     * @param listener Listener's object.
-     * @param errorType error type needs to be set in error message.
-     * @param parsableDataType type of parsable data in which error occurred.
+     * @param listener Listener's object
+     * @param errorType error type needs to be set in error message
+     * @param yangConstructType type of parsable data in which error occurred
      * @param parsableDataTypeName name of parsable data type in which error
-     *            occurred.
-     * @param errorLocation location where error occurred.
+     *            occurred
+     * @param errorLocation location where error occurred
      */
     public static void checkStackIsNotEmpty(TreeWalkListener listener, ListenerErrorType errorType,
-                                            ParsableDataType parsableDataType, String parsableDataTypeName,
+                                            YangConstructType yangConstructType, String parsableDataTypeName,
                                             ListenerErrorLocation errorLocation) {
         if (listener.getParsedDataStack().empty()) {
             /*
@@ -55,7 +58,7 @@
              * parsableDataTypeName will be null in case there is no name
              * attached to parsable data type.
              */
-            String message = constructListenerErrorMessage(errorType, parsableDataType, parsableDataTypeName,
+            String message = constructListenerErrorMessage(errorType, yangConstructType, parsableDataTypeName,
                                                            errorLocation);
             throw new ParserException(message);
         }
@@ -64,16 +67,15 @@
     /**
      * Checks parsed data stack is empty.
      *
-     * @param listener Listener's object.
-     * @param errorType error type needs to be set in error message.
-     * @param parsableDataType type of parsable data in which error occurred.
+     * @param listener Listener's object
+     * @param errorType error type needs to be set in error message
+     * @param yangConstructType type of parsable data in which error occurred
      * @param parsableDataTypeName name of parsable data type in which error
-     *            occurred.
-     * @param errorLocation location where error occurred.
+     *            occurred
+     * @param errorLocation location where error occurred
      */
-
     public static void checkStackIsEmpty(TreeWalkListener listener, ListenerErrorType errorType,
-                                         ParsableDataType parsableDataType, String parsableDataTypeName,
+                                         YangConstructType yangConstructType, String parsableDataTypeName,
                                          ListenerErrorLocation errorLocation) {
 
         if (!listener.getParsedDataStack().empty()) {
@@ -82,7 +84,7 @@
              * parsableDataTypeName will be null in case there is no name
              * attached to parsable data type.
              */
-            String message = constructListenerErrorMessage(errorType, parsableDataType, parsableDataTypeName,
+            String message = constructListenerErrorMessage(errorType, yangConstructType, parsableDataTypeName,
                                                            errorLocation);
             throw new ParserException(message);
         }
@@ -92,8 +94,8 @@
      * Returns parent node config value, if top node does not specify a config statement
      * then default value true is returned.
      *
-     * @param listener listener's object.
-     * @return true/false parent's config value.
+     * @param listener listener's object
+     * @return true/false parent's config value
      */
     public static boolean getParentNodeConfig(TreeWalkListener listener) {
         YangNode parentNode;
@@ -108,4 +110,71 @@
         }
         return true;
     }
+
+    /**
+     * Checks if a rule occurrences is as per the expected YANG grammar's
+     * cardinality.
+     *
+     * @param childContext child's context
+     * @param yangChildConstruct child construct for whom cardinality is to be
+     *                           validated
+     * @param yangParentConstruct parent construct
+     * @param parentName parent name
+     * @throws ParserException exception if cardinality check fails
+     */
+    public static void validateCardinality(List<?> childContext, YangConstructType yangChildConstruct,
+                                           YangConstructType yangParentConstruct, String parentName)
+            throws ParserException {
+
+        if (!childContext.isEmpty() && childContext.size() != 1) {
+            ParserException parserException = new ParserException("YANG file error: Invalid cardinality of "
+                    + getYangConstructType(yangChildConstruct) + " in " + getYangConstructType(yangParentConstruct)
+                    + " \"" + parentName + "\".");
+            throw parserException;
+        }
+    }
+
+    /**
+     * Checks if a rule occurrences is exactly 1.
+     *
+     * @param childContext child's context
+     * @param yangChildConstruct child construct for whom cardinality is to be
+     *                           validated
+     * @param yangParentConstruct parent construct
+     * @param parentName parent name
+     * @throws ParserException exception if cardinality check fails
+     */
+    public static void validateCardinalityEqualsOne(List<?> childContext, YangConstructType yangChildConstruct,
+                                                    YangConstructType yangParentConstruct, String parentName)
+            throws ParserException {
+
+        if (childContext.isEmpty() || childContext.size() != 1) {
+            ParserException parserException = new ParserException("YANG file error: Invalid cardinality of "
+                    + getYangConstructType(yangChildConstruct) + " in " + getYangConstructType(yangParentConstruct)
+                    + " \"" + parentName + "\".");
+            throw parserException;
+        }
+    }
+
+    /**
+     * Checks if a rule occurrences is minimum 1.
+     *
+     * @param childContext child's context
+     * @param yangChildConstruct child construct for whom cardinality is to be
+     *                           validated
+     * @param yangParentConstruct parent construct
+     * @param parentName parent name
+     * @throws ParserException exception if cardinality check fails
+     */
+    public static void validateCardinalityNonNull(List<?> childContext, YangConstructType yangChildConstruct,
+                                                  YangConstructType yangParentConstruct, String parentName)
+            throws ParserException {
+
+        if (childContext.isEmpty()) {
+            ParserException parserException = new ParserException("YANG file error: Invalid cardinality of "
+                    + getYangConstructType(yangChildConstruct) + " in " + getYangConstructType(yangParentConstruct)
+                    + " \"" + parentName + "\".");
+            throw parserException;
+        }
+    }
 }
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/ParsableDataType.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/utils/YangConstructType.java
similarity index 93%
rename from utils/yangutils/src/main/java/org/onosproject/yangutils/parser/ParsableDataType.java
rename to utils/yangutils/src/main/java/org/onosproject/yangutils/utils/YangConstructType.java
index 046a214..626674d 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/ParsableDataType.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/utils/YangConstructType.java
@@ -13,12 +13,12 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package org.onosproject.yangutils.parser;
+package org.onosproject.yangutils.utils;
 
 /**
  * ENUM to represent the type of data in parse tree.
  */
-public enum ParsableDataType {
+public enum YangConstructType {
     /**
      * Identifies the module parsed data.
      */
@@ -230,6 +230,11 @@
     POSITION_DATA,
 
     /**
+     * Identifies the YANG data definition statements.
+     */
+    DATA_DEF_DATA,
+
+    /**
      * Identifies the derived data type.
      */
     DERIVED;
@@ -237,12 +242,12 @@
     /**
      * Returns the YANG construct keyword corresponding to enum values.
      *
-     * @param parsableDataType enum value for parsable data type.
-     * @return YANG construct keyword.
+     * @param yangConstructType enum value for parsable data type
+     * @return YANG construct keyword
      */
-    public static String getParsableDataType(ParsableDataType parsableDataType) {
+    public static String getYangConstructType(YangConstructType yangConstructType) {
 
-        switch (parsableDataType) {
+        switch (yangConstructType) {
             case MODULE_DATA:
                 return "module";
             case SUB_MODULE_DATA:
@@ -327,6 +332,8 @@
                 return "position";
             case DEFAULT_DATA:
                 return "default";
+            case DATA_DEF_DATA:
+                return "data-def-substatements";
             case DERIVED:
                 return "derived";
             default:
diff --git a/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/impl/listeners/ContainerListenerTest.java b/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/impl/listeners/ContainerListenerTest.java
index aa86c51..961e902 100644
--- a/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/impl/listeners/ContainerListenerTest.java
+++ b/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/impl/listeners/ContainerListenerTest.java
@@ -69,6 +69,42 @@
     }
 
     /**
+     * Checks if container identifier in module is duplicate.
+     */
+    @Test(expected = ParserException.class)
+    public void processModuleDuplicateContainer() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/ModuleDuplicateContainer.yang");
+    }
+
+    /**
+     * Checks if container identifier in container is duplicate.
+     */
+    @Test(expected = ParserException.class)
+    public void processContainerDuplicateContainer() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/ContainerDuplicateContainer.yang");
+    }
+
+    /**
+     * Checks if container identifier in list is duplicate.
+     */
+    @Test(expected = ParserException.class)
+    public void processListDuplicateContainer() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/ListDuplicateContainer.yang");
+    }
+
+    /**
+     * Checks if container identifier collides with list at same level.
+     */
+    @Test(expected = ParserException.class)
+    public void processDuplicateContainerAndList() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/DuplicateContainerAndList.yang");
+    }
+
+    /**
      * Checks container statement as sub-statement of container.
      */
     @Test
@@ -170,7 +206,7 @@
     @Test
     public void processContainerSubStatementCardinality() throws IOException, ParserException {
         thrown.expect(ParserException.class);
-        thrown.expectMessage("Internal parser error detected: Invalid cardinality in reference before processing.");
+        thrown.expectMessage("YANG file error: Invalid cardinality of reference in container \"valid\".");
         YangNode node = manager.getDataModel("src/test/resources/ContainerSubStatementCardinality.yang");
     }
 
@@ -193,4 +229,4 @@
         thrown.expectMessage("mismatched input '1valid' expecting IDENTIFIER");
         YangNode node = manager.getDataModel("src/test/resources/ContainerInvalidIdentifier.yang");
     }
-}
\ No newline at end of file
+}
diff --git a/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/impl/listeners/LeafListListenerTest.java b/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/impl/listeners/LeafListListenerTest.java
index 359b108..afa48da 100644
--- a/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/impl/listeners/LeafListListenerTest.java
+++ b/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/impl/listeners/LeafListListenerTest.java
@@ -120,7 +120,7 @@
     @Test
     public void processLeafListConfigInvalidCardinality() throws IOException, ParserException {
         thrown.expect(ParserException.class);
-        thrown.expectMessage("Internal parser error detected: Invalid cardinality in config before processing.");
+        thrown.expectMessage("YANG file error: Invalid cardinality of config in leaf-list \"invalid-interval\".");
         YangNode node = manager.getDataModel("src/test/resources/LeafListConfigInvalidCardinality.yang");
     }
 
@@ -131,7 +131,7 @@
     @Test
     public void processLeafListUnitsInvalidCardinality() throws IOException, ParserException {
         thrown.expect(ParserException.class);
-        thrown.expectMessage("Internal parser error detected: Invalid cardinality in units before processing.");
+        thrown.expectMessage("YANG file error: Invalid cardinality of units in leaf-list \"invalid-interval\".");
         YangNode node = manager.getDataModel("src/test/resources/LeafListUnitsInvalidCardinality.yang");
     }
 
diff --git a/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/impl/listeners/LeafListenerTest.java b/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/impl/listeners/LeafListenerTest.java
index df8f385..40afc03 100644
--- a/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/impl/listeners/LeafListenerTest.java
+++ b/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/impl/listeners/LeafListenerTest.java
@@ -120,7 +120,7 @@
     @Test
     public void processLeafConfigInvalidCardinality() throws IOException, ParserException {
         thrown.expect(ParserException.class);
-        thrown.expectMessage("Internal parser error detected: Invalid cardinality in config before processing.");
+        thrown.expectMessage("YANG file error: Invalid cardinality of config in leaf \"invalid-interval\".");
         YangNode node = manager.getDataModel("src/test/resources/LeafConfigInvalidCardinality.yang");
     }
 
@@ -131,7 +131,7 @@
     @Test
     public void processLeafMandatoryInvalidCardinality() throws IOException, ParserException {
         thrown.expect(ParserException.class);
-        thrown.expectMessage("Internal parser error detected: Invalid cardinality in mandatory before processing.");
+        thrown.expectMessage("YANG file error: Invalid cardinality of mandatory in leaf \"invalid-interval\".");
         YangNode node = manager.getDataModel("src/test/resources/LeafMandatoryInvalidCardinality.yang");
     }
 
@@ -173,6 +173,33 @@
     }
 
     /**
+     * Checks duplicate leaf statement as sub-statement of module.
+     */
+    @Test(expected = ParserException.class)
+    public void processModuleWithDuplicateLeaf() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/ModuleWithDuplicateLeaf.yang");
+    }
+
+    /**
+     * Checks duplicate leaf statement as sub-statement of container.
+     */
+    @Test(expected = ParserException.class)
+    public void processContainerWithDuplicateLeaf() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/ContainerWithDuplicateLeaf.yang");
+    }
+
+    /**
+     * Checks duplicate leaf statement as sub-statement of list.
+     */
+    @Test(expected = ParserException.class)
+    public void processListWithDuplicateLeaf() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/ListWithDuplicateLeaf.yang");
+    }
+
+    /**
      * Checks leaf statement as sub-statement of list.
      */
     @Test
@@ -207,4 +234,4 @@
         assertThat(leafInfo.getStatus(), is(YangStatusType.CURRENT));
         assertThat(leafInfo.getReference(), is("\"RFC 6020\""));
     }
-}
\ No newline at end of file
+}
diff --git a/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/impl/listeners/ListListenerTest.java b/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/impl/listeners/ListListenerTest.java
index 0d2d29b..fdc2221 100644
--- a/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/impl/listeners/ListListenerTest.java
+++ b/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/impl/listeners/ListListenerTest.java
@@ -175,7 +175,7 @@
     @Test
     public void processListSubStatementsCardinality() throws IOException, ParserException {
         thrown.expect(ParserException.class);
-        thrown.expectMessage("Internal parser error detected: Invalid cardinality in reference before processing.");
+        thrown.expectMessage("YANG file error: Invalid cardinality of reference in list \"valid\".");
         YangNode node = manager.getDataModel("src/test/resources/ListSubStatementsCardinality.yang");
     }
 
@@ -185,7 +185,7 @@
     @Test
     public void processListStatementWithoutChild() throws IOException, ParserException {
         thrown.expect(ParserException.class);
-        thrown.expectMessage("Internal parser error detected: Invalid cardinality in list before processing.");
+        thrown.expectMessage("YANG file error: Invalid cardinality of data-def-substatements in list \"valid\".");
         YangNode node = manager.getDataModel("src/test/resources/ListStatementWithoutChild.yang");
     }
 
diff --git a/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/impl/listeners/MaxElementsListenerTest.java b/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/impl/listeners/MaxElementsListenerTest.java
index f3f3876..f70dc96 100644
--- a/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/impl/listeners/MaxElementsListenerTest.java
+++ b/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/impl/listeners/MaxElementsListenerTest.java
@@ -122,7 +122,7 @@
     @Test
     public void processMaxElementsCardinality() throws IOException, ParserException {
         thrown.expect(ParserException.class);
-        thrown.expectMessage("Internal parser error detected: Invalid cardinality in max-elements before processing.");
+        thrown.expectMessage("YANG file error: Invalid cardinality of max-elements in leaf-list \"invalid-interval\".");
         YangNode node = manager.getDataModel("src/test/resources/MaxElementsCardinality.yang");
     }
 
diff --git a/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/impl/listeners/MinElementsListenerTest.java b/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/impl/listeners/MinElementsListenerTest.java
index c8a5576..b197557 100644
--- a/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/impl/listeners/MinElementsListenerTest.java
+++ b/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/impl/listeners/MinElementsListenerTest.java
@@ -133,8 +133,7 @@
     @Test
     public void processMinElementsInvalidCardinality() throws IOException, ParserException {
         thrown.expect(ParserException.class);
-        thrown.expectMessage(
-                "Internal parser error detected: Invalid cardinality in" + " min-elements before processing.");
+        thrown.expectMessage("YANG file error: Invalid cardinality of min-elements in leaf-list \"invalid-interval\".");
         YangNode node = manager.getDataModel("src/test/resources/MinElementsInvalidCardinality.yang");
     }
 
diff --git a/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/impl/listeners/UnitsListenerTest.java b/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/impl/listeners/UnitsListenerTest.java
index c4b9fa7..53611fe 100644
--- a/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/impl/listeners/UnitsListenerTest.java
+++ b/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/impl/listeners/UnitsListenerTest.java
@@ -157,7 +157,7 @@
     @Test
     public void processUnitsStatementCardinality() throws IOException, ParserException {
         thrown.expect(ParserException.class);
-        thrown.expectMessage("Internal parser error detected: Invalid cardinality in units before processing.");
+        thrown.expectMessage("YANG file error: Invalid cardinality of units in leaf \"invalid-interval\".");
         YangNode node = manager.getDataModel("src/test/resources/UnitsStatementCardinality.yang");
     }
 
diff --git a/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/impl/listeners/VersionListenerTest.java b/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/impl/listeners/VersionListenerTest.java
index 2338604..e13e987 100644
--- a/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/impl/listeners/VersionListenerTest.java
+++ b/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/impl/listeners/VersionListenerTest.java
@@ -64,7 +64,7 @@
         YangNode node = manager.getDataModel("src/test/resources/VersionNotPresent.yang");
 
         // Checks for the version value in data model tree.
-        assertThat(((YangModule) node).getVersion(), is((byte) 0));
+        assertThat(((YangModule) node).getVersion(), is((byte) 1));
     }
 
     /**
diff --git a/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/parseutils/ListenerErrorMessageConstructionTest.java b/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/parseutils/ListenerErrorMessageConstructionTest.java
index 0c1473e..9486f50 100644
--- a/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/parseutils/ListenerErrorMessageConstructionTest.java
+++ b/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/parseutils/ListenerErrorMessageConstructionTest.java
@@ -20,7 +20,7 @@
 
 import static org.hamcrest.core.Is.is;
 import static org.junit.Assert.assertThat;
-import static org.onosproject.yangutils.parser.ParsableDataType.CONTACT_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.CONTACT_DATA;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructExtendedListenerErrorMessage;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
diff --git a/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/parseutils/ListenerValidationTest.java b/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/parseutils/ListenerValidationTest.java
index d39b0ae..e9843d6 100644
--- a/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/parseutils/ListenerValidationTest.java
+++ b/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/parseutils/ListenerValidationTest.java
@@ -23,7 +23,7 @@
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
 
-import static org.onosproject.yangutils.parser.ParsableDataType.YANGBASE_DATA;
+import static org.onosproject.yangutils.utils.YangConstructType.YANGBASE_DATA;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.EXIT;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
 import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_HOLDER;
diff --git a/utils/yangutils/src/test/resources/ContainerDuplicateContainer.yang b/utils/yangutils/src/test/resources/ContainerDuplicateContainer.yang
new file mode 100644
index 0000000..4928463
--- /dev/null
+++ b/utils/yangutils/src/test/resources/ContainerDuplicateContainer.yang
@@ -0,0 +1,23 @@
+module Test {
+    yang-version 1;
+    namespace http://huawei.com;
+    prefix Ant;
+    container ospf {
+        container valid {
+            leaf invalid-interval {
+                type "uint16";
+                units "seconds";
+                status current;
+                reference "RFC 6020";
+            }
+        }
+        container valid {
+            leaf invalid-interval {
+                type "uint16";
+                units "seconds";
+                status current;
+                reference "RFC 6020";
+            }
+        }
+    }
+}
diff --git a/utils/yangutils/src/test/resources/ContainerWithDuplicateLeaf.yang b/utils/yangutils/src/test/resources/ContainerWithDuplicateLeaf.yang
new file mode 100644
index 0000000..3adaccd
--- /dev/null
+++ b/utils/yangutils/src/test/resources/ContainerWithDuplicateLeaf.yang
@@ -0,0 +1,34 @@
+module Test {
+    yang-version 1;
+    namespace http://huawei.com;
+    prefix Ant;
+    container valid {
+        leaf invalid-interval {
+            type "uint16";
+            units "seconds";
+            description "Interval before a route is declared invalid";
+            config true;
+            mandatory true;
+            status current;
+            reference "RFC 6020";
+        }
+        leaf valid-interval {
+            type "uint16";
+            units "seconds";
+            description "Interval before a route is declared invalid";
+            config true;
+            mandatory true;
+            status current;
+            reference "RFC 6020";
+        }
+        leaf valid-interval {
+            type "uint16";
+            units "seconds";
+            description "Interval before a route is declared invalid";
+            config true;
+            mandatory true;
+            status current;
+            reference "RFC 6020";
+        }
+    }
+}
diff --git a/utils/yangutils/src/test/resources/DuplicateContainerAndList.yang b/utils/yangutils/src/test/resources/DuplicateContainerAndList.yang
new file mode 100644
index 0000000..74c7721
--- /dev/null
+++ b/utils/yangutils/src/test/resources/DuplicateContainerAndList.yang
@@ -0,0 +1,29 @@
+module Test {
+    yang-version 1;
+    namespace http://huawei.com;
+    prefix Ant;
+    container ospf {
+        container valid {
+            leaf invalid-interval {
+                type "uint16";
+                units "seconds";
+                status current;
+                reference "RFC 6020";
+            }
+        }
+        list valid {
+            key "process-id";
+            container interface {
+                leaf invalid-interval {
+                    type "uint16";
+                    units "seconds";
+                    status current;
+                    reference "RFC 6020";
+                }
+            }
+            leaf process-id {
+                type "string";
+            }
+        }
+    }
+}
diff --git a/utils/yangutils/src/test/resources/ListDuplicateContainer.yang b/utils/yangutils/src/test/resources/ListDuplicateContainer.yang
new file mode 100644
index 0000000..8c152b2
--- /dev/null
+++ b/utils/yangutils/src/test/resources/ListDuplicateContainer.yang
@@ -0,0 +1,27 @@
+module Test {
+    yang-version 1;
+    namespace http://huawei.com;
+    prefix Ant;
+    list ospf {
+        key "process-id";
+        container interface {
+            leaf invalid-interval {
+                type "uint16";
+                units "seconds";
+                status current;
+                reference "RFC 6020";
+            }
+        }
+        leaf process-id {
+            type "string";
+        }
+        container interface {
+            leaf invalid-interval {
+                type "uint16";
+                units "seconds";
+                status current;
+                reference "RFC 6020";
+            }
+        }
+    }
+}
diff --git a/utils/yangutils/src/test/resources/ListWithDuplicateLeaf.yang b/utils/yangutils/src/test/resources/ListWithDuplicateLeaf.yang
new file mode 100644
index 0000000..55a78f6
--- /dev/null
+++ b/utils/yangutils/src/test/resources/ListWithDuplicateLeaf.yang
@@ -0,0 +1,26 @@
+module Test {
+    yang-version 1;
+    namespace http://huawei.com;
+    prefix Ant;
+    list valid {
+        key "invalid-interval";
+        leaf invalid-interval {
+            type "uint16";
+            units "seconds";
+            description "Interval before a route is declared invalid";
+            config true;
+            mandatory true;
+            status current;
+            reference "RFC 6020";
+        }
+        leaf invalid-interval {
+            type "uint16";
+            units "seconds";
+            description "Interval before a route is declared invalid";
+            config true;
+            mandatory true;
+            status current;
+            reference "RFC 6020";
+        }
+    }
+}
diff --git a/utils/yangutils/src/test/resources/ModuleDuplicateContainer.yang b/utils/yangutils/src/test/resources/ModuleDuplicateContainer.yang
new file mode 100644
index 0000000..bc58896
--- /dev/null
+++ b/utils/yangutils/src/test/resources/ModuleDuplicateContainer.yang
@@ -0,0 +1,29 @@
+module Test {
+    yang-version 1;
+    namespace http://huawei.com;
+    prefix Ant;
+    container valid {
+        leaf invalid-interval {
+            type "uint16";
+            units "seconds";
+            status current;
+            reference "RFC 6020";
+        }
+    }
+    container invalid {
+        leaf invalid-interval {
+            type "uint16";
+            units "seconds";
+            status current;
+            reference "RFC 6020";
+        }
+    }
+    container valid {
+        leaf invalid-interval {
+            type "uint16";
+            units "seconds";
+            status current;
+            reference "RFC 6020";
+        }
+    }
+}
diff --git a/utils/yangutils/src/test/resources/ModuleWithDuplicateLeaf.yang b/utils/yangutils/src/test/resources/ModuleWithDuplicateLeaf.yang
new file mode 100644
index 0000000..2c3ecbc
--- /dev/null
+++ b/utils/yangutils/src/test/resources/ModuleWithDuplicateLeaf.yang
@@ -0,0 +1,32 @@
+module Test {
+    yang-version 1;
+    namespace http://huawei.com;
+    prefix Ant;
+    leaf invalid-interval {
+        type "uint16";
+        units "seconds";
+        description "Interval before a route is declared invalid";
+        config true;
+        mandatory true;
+        status current;
+        reference "RFC 6020";
+    }
+    leaf valid-interval {
+        type "uint16";
+        units "seconds";
+        description "Interval before a route is declared invalid";
+        config true;
+        mandatory true;
+        status current;
+        reference "RFC 6020";
+    }
+    leaf invalid-interval {
+        type "uint16";
+        units "seconds";
+        description "Interval before a route is declared invalid";
+        config true;
+        mandatory true;
+        status current;
+        reference "RFC 6020";
+    }
+}