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 5e33e36..77f19c1 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
@@ -20,6 +20,8 @@
 import org.onosproject.yangutils.parser.Parsable;
 import org.onosproject.yangutils.parser.ParsableDataType;
 
+import java.util.Objects;
+
 /*-
  *  The "bit" statement, which is a sub-statement to the "type" statement,
  *  MUST be present if the type is "bits".  It is repeatedly used to
@@ -57,7 +59,7 @@
     private String description;
 
     /**
-     * reference info of the bit field.
+     * Reference info of the bit field.
      */
     private String reference;
 
@@ -67,7 +69,7 @@
     private YangStatusType status;
 
     /**
-     * position of the bit whose name bit is described.
+     * Position of the bit whose name bit is described.
      */
     private int position;
 
@@ -79,7 +81,7 @@
     }
 
     /**
-     * Get the bit name.
+     * Returns bit name.
      *
      * @return the bit name.
      */
@@ -97,7 +99,7 @@
     }
 
     /**
-     * Get the description.
+     * Returns description.
      *
      * @return the description.
      */
@@ -117,7 +119,7 @@
     }
 
     /**
-     * Get the textual reference.
+     * Returns textual reference.
      *
      * @return the reference.
      */
@@ -137,7 +139,7 @@
     }
 
     /**
-     * Get the status.
+     * Returns status.
      *
      * @return the status.
      */
@@ -157,7 +159,7 @@
     }
 
     /**
-     * Get the bit position.
+     * Returns bit position.
      *
      * @return the position
      */
@@ -184,6 +186,23 @@
         return ParsableDataType.BIT_DATA;
     }
 
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+        if (obj instanceof YangBit) {
+            final YangBit other = (YangBit) obj;
+            return Objects.equals(this.bitName, other.bitName);
+        }
+        return false;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hashCode(this.bitName);
+    }
+
     /**
      * Validate the data on entering the corresponding parse tree node.
      *
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 d519925..54898a4 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
@@ -36,8 +36,12 @@
  */
 public class YangBits implements Parsable {
 
+    // Bits information set.
     private Set<YangBit> bitSet;
 
+    // BITS name.
+    private String bitsName;
+
     /**
      * Create a YANG bits type object.
      */
@@ -46,7 +50,7 @@
     }
 
     /**
-     * Get the bit set.
+     * Returns the bit set.
      *
      * @return the bit set
      */
@@ -55,7 +59,7 @@
     }
 
     /**
-     * set the bit set.
+     * Set the bit set.
      *
      * @param bitSet the bit set
      */
@@ -66,10 +70,13 @@
     /**
      * Add bit info.
      *
-     * @param bitInfo the bit Info to add.
+     * @param bitInfo the bit information to be added.
+     * @throws DataModelException due to violation in data model rules.
      */
-    public void addBitInfo(YangBit bitInfo) {
-        getBitSet().add(bitInfo);
+    public void addBitInfo(YangBit bitInfo) throws DataModelException {
+        if (!getBitSet().add(bitInfo)) {
+            throw new DataModelException("YANG Bit already exists");
+        }
     }
 
     /**
@@ -83,6 +90,24 @@
     }
 
     /**
+     * Returns the bits name.
+     *
+     * @return name of the bits.
+     */
+    public String getBitsName() {
+        return bitsName;
+    }
+
+    /**
+     * Set bits name.
+     *
+     * @param bitsName bit name to be set.
+     */
+    public void setBitsName(String bitsName) {
+        this.bitsName = bitsName;
+    }
+
+    /**
      * Validate the data on entering the corresponding parse tree node.
      *
      * @throws DataModelException a violation of data model rules.
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/ParsableDataType.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/ParsableDataType.java
index 9d2cfb0..046a214 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/ParsableDataType.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/ParsableDataType.java
@@ -225,6 +225,11 @@
     ORGANIZATION_DATA,
 
     /**
+     * Identifies the YANG position element parsed data.
+     */
+    POSITION_DATA,
+
+    /**
      * Identifies the derived data type.
      */
     DERIVED;
@@ -318,6 +323,8 @@
                 return "organization";
             case VALUE_DATA:
                 return "value";
+            case POSITION_DATA:
+                return "position";
             case DEFAULT_DATA:
                 return "default";
             case DERIVED:
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 20e086f..e2f4d70 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
@@ -27,6 +27,8 @@
 import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
 import org.onosproject.yangutils.parser.impl.listeners.BaseFileListener;
 import org.onosproject.yangutils.parser.impl.listeners.BelongsToListener;
+import org.onosproject.yangutils.parser.impl.listeners.BitListener;
+import org.onosproject.yangutils.parser.impl.listeners.BitsListener;
 import org.onosproject.yangutils.parser.impl.listeners.ConfigListener;
 import org.onosproject.yangutils.parser.impl.listeners.ContactListener;
 import org.onosproject.yangutils.parser.impl.listeners.ContainerListener;
@@ -46,6 +48,7 @@
 import org.onosproject.yangutils.parser.impl.listeners.ModuleListener;
 import org.onosproject.yangutils.parser.impl.listeners.NamespaceListener;
 import org.onosproject.yangutils.parser.impl.listeners.OrganizationListener;
+import org.onosproject.yangutils.parser.impl.listeners.PositionListener;
 import org.onosproject.yangutils.parser.impl.listeners.PrefixListener;
 import org.onosproject.yangutils.parser.impl.listeners.PresenceListener;
 import org.onosproject.yangutils.parser.impl.listeners.ReferenceListener;
@@ -691,22 +694,22 @@
 
     @Override
     public void enterBitsSpecification(GeneratedYangParser.BitsSpecificationContext ctx) {
-        // TODO: implement the method.
+        BitsListener.processBitsEntry(this, ctx);
     }
 
     @Override
     public void exitBitsSpecification(GeneratedYangParser.BitsSpecificationContext ctx) {
-        // TODO: implement the method.
+        BitsListener.processBitsExit(this, ctx);
     }
 
     @Override
     public void enterBitStatement(GeneratedYangParser.BitStatementContext ctx) {
-        // TODO: implement the method.
+        BitListener.processBitEntry(this, ctx);
     }
 
     @Override
     public void exitBitStatement(GeneratedYangParser.BitStatementContext ctx) {
-        // TODO: implement the method.
+        BitListener.processBitExit(this, ctx);
     }
 
     @Override
@@ -721,7 +724,7 @@
 
     @Override
     public void enterPositionStatement(GeneratedYangParser.PositionStatementContext ctx) {
-        // TODO: implement the method.
+        PositionListener.processPositionEntry(this, ctx);
     }
 
     @Override
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
new file mode 100644
index 0000000..a574091
--- /dev/null
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/BitListener.java
@@ -0,0 +1,171 @@
+/*
+ * Copyright 2014-2016 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.listeners;
+
+/*
+ * Reference: RFC6020 and YANG ANTLR Grammar
+ *
+ * ABNF grammar as per RFC6020
+ * bit-stmt            = bit-keyword sep identifier-arg-str optsep
+ *                       (";" /
+ *                        "{" stmtsep
+ *                            ;; these stmts can appear in any order
+ *                            [position-stmt stmtsep]
+ *                            [status-stmt stmtsep]
+ *                            [description-stmt stmtsep]
+ *                            [reference-stmt stmtsep]
+ *                          "}"
+ *                        "}")
+ *
+ * ANTLR grammar rule
+ * bitStatement : BIT_KEYWORD IDENTIFIER (STMTEND | LEFT_CURLY_BRACE bitBodyStatement RIGHT_CURLY_BRACE);
+ *
+ * bitBodyStatement : positionStatement? statusStatement? descriptionStatement? referenceStatement?
+ *               | positionStatement? statusStatement? referenceStatement? descriptionStatement?
+ *               | positionStatement? descriptionStatement? statusStatement? referenceStatement?
+ *               | positionStatement? descriptionStatement? referenceStatement? statusStatement?
+ *               | positionStatement? referenceStatement? statusStatement? descriptionStatement?
+ *               | positionStatement? referenceStatement? descriptionStatement? statusStatement?
+ *               | statusStatement? positionStatement? descriptionStatement? referenceStatement?
+ *               | statusStatement? positionStatement? referenceStatement? descriptionStatement?
+ *               | statusStatement? descriptionStatement? descriptionStatement? positionStatement?
+ *               | statusStatement? descriptionStatement? positionStatement? descriptionStatement?
+ *               | statusStatement? referenceStatement? positionStatement? descriptionStatement?
+ *               | statusStatement? referenceStatement? descriptionStatement? positionStatement?
+ *               | descriptionStatement? positionStatement? statusStatement? referenceStatement?
+ *               | descriptionStatement? positionStatement? referenceStatement? statusStatement?
+ *               | descriptionStatement? statusStatement? positionStatement? referenceStatement?
+ *               | descriptionStatement? statusStatement? referenceStatement? positionStatement?
+ *               | descriptionStatement? referenceStatement? positionStatement? statusStatement?
+ *               | descriptionStatement? referenceStatement? statusStatement? positionStatement?
+ *               | referenceStatement? positionStatement? descriptionStatement? statusStatement?
+ *               | referenceStatement? positionStatement? statusStatement? descriptionStatement?
+ *               | referenceStatement? statusStatement? descriptionStatement? positionStatement?
+ *               | referenceStatement? statusStatement? positionStatement? descriptionStatement?
+ *               | referenceStatement? descriptionStatement? positionStatement? statusStatement?
+ *               | referenceStatement? descriptionStatement? statusStatement? positionStatement?
+ *               ;
+ */
+
+import org.onosproject.yangutils.datamodel.YangBit;
+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 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.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_CONTENT;
+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;
+
+/**
+ * Implements listener based call back function corresponding to the "bit"
+ * rule defined in ANTLR grammar file for corresponding ABNF rule in RFC 6020.
+ */
+public final class BitListener {
+
+    /**
+     * Creates a new bit listener.
+     */
+    private BitListener() {
+    }
+
+    /**
+     * 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.
+     */
+    public static void processBitEntry(TreeWalkListener listener,
+                                        GeneratedYangParser.BitStatementContext ctx) {
+
+        // Check for stack to be non empty.
+        checkStackIsNotEmpty(listener, MISSING_HOLDER, BIT_DATA, ctx.IDENTIFIER().getText(), ENTRY);
+
+        YangBit bitNode = new YangBit();
+        bitNode.setBitName(ctx.IDENTIFIER().getText());
+        listener.getParsedDataStack().push(bitNode);
+    }
+
+    /**
+     * 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.
+     */
+    public static void processBitExit(TreeWalkListener listener,
+                                       GeneratedYangParser.BitStatementContext ctx) {
+
+        // Check for stack to be non empty.
+        checkStackIsNotEmpty(listener, MISSING_HOLDER, BIT_DATA, ctx.IDENTIFIER().getText(), EXIT);
+
+        Parsable tmpBitNode = listener.getParsedDataStack().peek();
+        if (tmpBitNode instanceof YangBit) {
+            listener.getParsedDataStack().pop();
+
+            // Check for stack to be non empty.
+            checkStackIsNotEmpty(listener, MISSING_HOLDER, BIT_DATA, ctx.IDENTIFIER().getText(), EXIT);
+
+            Parsable tmpNode = listener.getParsedDataStack().peek();
+            switch (tmpNode.getParsableDataType()) {
+                case BITS_DATA: {
+                    YangBits yangBits = (YangBits) tmpNode;
+                    if ((ctx.bitBodyStatement() == null) || (ctx.bitBodyStatement().positionStatement() == null)) {
+                        int maxPosition = 0;
+                        boolean isPositionPresent = false;
+
+                        for (YangBit curBit : yangBits.getBitSet()) {
+                            if (maxPosition <= curBit.getPosition()) {
+                                maxPosition = curBit.getPosition();
+                                isPositionPresent = true;
+                            }
+                        }
+                        if (isPositionPresent) {
+                            maxPosition++;
+                        }
+                        ((YangBit) tmpBitNode).setPosition(maxPosition);
+                    }
+                    try {
+                        yangBits.addBitInfo((YangBit) tmpBitNode);
+                    } catch (DataModelException e) {
+                        ParserException parserException = new ParserException(constructExtendedListenerErrorMessage(
+                                INVALID_CONTENT, BIT_DATA, ctx.IDENTIFIER().getText(), EXIT, e.getMessage()));
+                        parserException.setLine(ctx.IDENTIFIER().getSymbol().getLine());
+                        parserException.setCharPosition(ctx.IDENTIFIER().getSymbol().getCharPositionInLine());
+                        throw parserException;
+                    }
+                    break;
+                }
+                default:
+                    throw new ParserException(
+                            constructListenerErrorMessage(INVALID_HOLDER, BIT_DATA, ctx.IDENTIFIER().getText(), EXIT));
+            }
+        } else {
+            throw new ParserException(
+                    constructListenerErrorMessage(MISSING_CURRENT_HOLDER, BIT_DATA, ctx.IDENTIFIER().getText(), EXIT));
+        }
+    }
+}
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
new file mode 100644
index 0000000..d8f8467
--- /dev/null
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/BitsListener.java
@@ -0,0 +1,151 @@
+/*
+ * Copyright 2014-2016 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.listeners;
+
+/*
+ * Reference: RFC6020 and YANG ANTLR Grammar
+ *
+ * ABNF grammar as per RFC6020
+ * type-body-stmts     = numerical-restrictions /
+ *                       decimal64-specification /
+ *                      string-restrictions /
+ *                       enum-specification /
+ *                       leafref-specification /
+ *                       identityref-specification /
+ *                       instance-identifier-specification /
+ *                       bits-specification /
+ *                       union-specification
+ *
+ * bits-specification  = 1*(bit-stmt stmtsep)
+ *
+ * ANTLR grammar rule
+ *
+ * typeBodyStatements : numericalRestrictions | stringRestrictions | enumSpecification
+ *                 | leafrefSpecification | identityrefSpecification | instanceIdentifierSpecification
+ *                 | bitsSpecification | unionSpecification;
+ *
+ * bitsSpecification : bitStatement+;
+ */
+
+import org.onosproject.yangutils.datamodel.YangBits;
+import org.onosproject.yangutils.datamodel.YangLeaf;
+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 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.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_CURRENT_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.MISSING_HOLDER;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.checkStackIsNotEmpty;
+
+/**
+ * Implements listener based call back function corresponding to the "bits"
+ * rule defined in ANTLR grammar file for corresponding ABNF rule in RFC 6020.
+ */
+public final class BitsListener {
+
+    /**
+     * Creates a new bits listener.
+     */
+    private BitsListener() {
+    }
+
+    /**
+     * 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.
+     */
+    public static void processBitsEntry(TreeWalkListener listener,
+                                               GeneratedYangParser.BitsSpecificationContext ctx) {
+
+        // Check for stack to be non empty.
+        checkStackIsNotEmpty(listener, MISSING_HOLDER, BITS_DATA, "", ENTRY);
+
+        if (listener.getParsedDataStack().peek() instanceof YangType) {
+            YangBits bitsNode = new YangBits();
+            Parsable typeData = listener.getParsedDataStack().pop();
+
+            // Check for stack to be non empty.
+            checkStackIsNotEmpty(listener, MISSING_HOLDER, BITS_DATA, "", ENTRY);
+
+            Parsable tmpData = listener.getParsedDataStack().peek();
+
+            switch (tmpData.getParsableDataType()) {
+                case LEAF_DATA:
+                    bitsNode.setBitsName(((YangLeaf) tmpData).getLeafName());
+                    break;
+                case LEAF_LIST_DATA:
+                    bitsNode.setBitsName(((YangLeafList) tmpData).getLeafName());
+                    break;
+                // TODO typedef, union, deviate.
+                default:
+                    throw new ParserException(constructListenerErrorMessage(INVALID_HOLDER, TYPE_DATA,
+                            ((YangType) typeData).getDataTypeName(), ENTRY));
+            }
+            listener.getParsedDataStack().push(typeData);
+            listener.getParsedDataStack().push(bitsNode);
+        } else {
+            throw new ParserException(constructListenerErrorMessage(INVALID_HOLDER, BITS_DATA, "", ENTRY));
+        }
+    }
+
+    /**
+     * 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.
+     */
+    public static void processBitsExit(TreeWalkListener listener,
+                                              GeneratedYangParser.BitsSpecificationContext ctx) {
+
+        // Check for stack to be non empty.
+        checkStackIsNotEmpty(listener, MISSING_HOLDER, BITS_DATA, "", EXIT);
+
+        Parsable tmpBitsNode = listener.getParsedDataStack().peek();
+        if (tmpBitsNode instanceof YangBits) {
+            listener.getParsedDataStack().pop();
+
+            // Check for stack to be non empty.
+            checkStackIsNotEmpty(listener, MISSING_HOLDER, BITS_DATA, "", EXIT);
+
+            Parsable tmpNode = listener.getParsedDataStack().peek();
+            switch (tmpNode.getParsableDataType()) {
+                case TYPE_DATA: {
+                    YangType typeNode = (YangType) tmpNode;
+                    typeNode.setDataTypeExtendedInfo((YangBits) tmpBitsNode);
+                    break;
+                }
+                default:
+                    throw new ParserException(
+                            constructListenerErrorMessage(INVALID_HOLDER, BITS_DATA, "", EXIT));
+            }
+        } else {
+            throw new ParserException(
+                    constructListenerErrorMessage(MISSING_CURRENT_HOLDER, BITS_DATA, "", EXIT));
+        }
+    }
+}
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
new file mode 100644
index 0000000..92b3e68
--- /dev/null
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/PositionListener.java
@@ -0,0 +1,137 @@
+/*
+ * Copyright 2014-2016 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.listeners;
+
+/*
+ * Reference: RFC6020 and YANG ANTLR Grammar
+ *
+ * ABNF grammar as per RFC6020
+ * position-stmt       = position-keyword sep
+ *                       position-value-arg-str stmtend
+ * position-value-arg-str = < a string that matches the rule
+ *                            position-value-arg >
+ * position-value-arg  = non-negative-integer-value
+ * non-negative-integer-value = "0" / positive-integer-value
+ * positive-integer-value = (non-zero-digit *DIGIT)
+ * zero-integer-value  = 1*DIGIT
+ *
+ * ANTLR grammar rule
+ * positionStatement : POSITION_KEYWORD INTEGER STMTEND;
+ */
+
+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 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.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;
+
+/**
+ * Implements listener based call back function corresponding to the "position"
+ * rule defined in ANTLR grammar file for corresponding ABNF rule in RFC 6020.
+ */
+public final class PositionListener {
+
+    // Exact message in case position is invalid.
+    private static String errMsg;
+
+    /**
+     * Creates a new position listener.
+     */
+    private PositionListener() {
+    }
+
+    /**
+     * 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.
+     */
+    public static void processPositionEntry(TreeWalkListener listener,
+                                            GeneratedYangParser.PositionStatementContext ctx) {
+
+        // Check for stack to be non empty.
+        checkStackIsNotEmpty(listener, MISSING_HOLDER, POSITION_DATA, ctx.INTEGER().getText(), ENTRY);
+
+        // Obtain the node of the stack.
+        Parsable tmpNode = listener.getParsedDataStack().peek();
+        switch (tmpNode.getParsableDataType()) {
+            case BIT_DATA: {
+                YangBit bitNode = (YangBit) tmpNode;
+                if (!isBitPositionValid(listener, ctx)) {
+                    ParserException parserException = new ParserException(errMsg);
+                    parserException.setLine(ctx.INTEGER().getSymbol().getLine());
+                    parserException.setCharPosition(ctx.INTEGER().getSymbol().getCharPositionInLine());
+                    throw parserException;
+                }
+                bitNode.setPosition(Integer.valueOf(ctx.INTEGER().getText()));
+                break;
+            }
+            default:
+                throw new ParserException(
+                        constructListenerErrorMessage(INVALID_HOLDER, POSITION_DATA, ctx.INTEGER().getText(), ENTRY));
+        }
+    }
+
+    /**
+     * Validates BITS position value correctness and uniqueness.
+     *
+     * @param listener Listener's object.
+     * @param ctx context object of the grammar rule.
+     * @return validation result
+     */
+    private static boolean isBitPositionValid(TreeWalkListener listener,
+                                           GeneratedYangParser.PositionStatementContext ctx) {
+        Parsable bitNode = listener.getParsedDataStack().pop();
+
+        // Check for stack to be non empty.
+        checkStackIsNotEmpty(listener, MISSING_HOLDER, POSITION_DATA, ctx.INTEGER().getText(), ENTRY);
+
+        if (Integer.valueOf(ctx.INTEGER().getText()) < 0) {
+            errMsg = "Negative value of position is invalid";
+            listener.getParsedDataStack().push(bitNode);
+            return false;
+        }
+
+        Parsable tmpNode = listener.getParsedDataStack().peek();
+        switch (tmpNode.getParsableDataType()) {
+            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";
+                        listener.getParsedDataStack().push(bitNode);
+                        return false;
+                    }
+                }
+                listener.getParsedDataStack().push(bitNode);
+                return true;
+            }
+            default:
+                listener.getParsedDataStack().push(bitNode);
+                throw new ParserException(
+                        constructListenerErrorMessage(INVALID_HOLDER, POSITION_DATA, ctx.INTEGER().getText(), ENTRY));
+        }
+    }
+}
\ No newline at end of file
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 07ada45..7c050dc 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
@@ -34,7 +34,6 @@
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
 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;
@@ -70,7 +69,7 @@
             case ENUM_DATA: {
                 YangEnum enumNode = (YangEnum) tmpNode;
                 if (!isEnumValueValid(listener, ctx)) {
-                    ParserException parserException = new ParserException("Input version not supported");
+                    ParserException parserException = new ParserException("Duplicate Value Entry");
                     parserException.setLine(ctx.INTEGER().getSymbol().getLine());
                     parserException.setCharPosition(ctx.INTEGER().getSymbol().getCharPositionInLine());
                     throw parserException;
@@ -93,6 +92,10 @@
      */
     private static boolean isEnumValueValid(TreeWalkListener listener, GeneratedYangParser.ValueStatementContext ctx) {
         Parsable enumNode = listener.getParsedDataStack().pop();
+
+        // Check for stack to be non empty.
+        checkStackIsNotEmpty(listener, MISSING_HOLDER, VALUE_DATA, ctx.INTEGER().getText(), ENTRY);
+
         Parsable tmpNode = listener.getParsedDataStack().peek();
         switch (tmpNode.getParsableDataType()) {
             case ENUMERATION_DATA: {
@@ -109,7 +112,7 @@
             default:
                 listener.getParsedDataStack().push(enumNode);
                 throw new ParserException(
-                        constructListenerErrorMessage(INVALID_HOLDER, VALUE_DATA, ctx.INTEGER().getText(), EXIT));
+                        constructListenerErrorMessage(INVALID_HOLDER, VALUE_DATA, ctx.INTEGER().getText(), ENTRY));
         }
     }
 }
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 e28d186..1d061d7 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
@@ -55,6 +55,11 @@
     DUPLICATE_ENTRY(),
 
     /**
+     * Represents that the content is invalid.
+     */
+    INVALID_CONTENT(),
+
+    /**
      * Represents that some of earlier parsed data is not handled correctly.
      */
     UNHANDLED_PARSED_DATA();
@@ -80,6 +85,8 @@
                 return "Invalid cardinality in";
             case DUPLICATE_ENTRY:
                 return "Duplicate";
+            case INVALID_CONTENT:
+                return "Invalid content in";
             case UNHANDLED_PARSED_DATA:
                 return "Unhandled parsed data at";
             default: