diff --git a/core/api/src/main/java/org/onosproject/ui/topo/Mod.java b/core/api/src/main/java/org/onosproject/ui/topo/Mod.java
new file mode 100644
index 0000000..d21a872
--- /dev/null
+++ b/core/api/src/main/java/org/onosproject/ui/topo/Mod.java
@@ -0,0 +1,66 @@
+/*
+ * Copyright 2015 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.ui.topo;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+/**
+ * Highlighting modification.
+ * <p>
+ * Note that (for link highlights) this translates to a CSS class name
+ * that is applied to the link in the Topology UI.
+ */
+public final class Mod implements Comparable<Mod> {
+    private final String modId;
+
+    /**
+     * Constructs a mod with the given identifier.
+     *
+     * @param modId modification identifier
+     */
+    public Mod(String modId) {
+        this.modId = checkNotNull(modId);
+    }
+
+    @Override
+    public String toString() {
+        return modId;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) {
+            return true;
+        }
+        if (o == null || getClass() != o.getClass()) {
+            return false;
+        }
+        Mod mod = (Mod) o;
+        return modId.equals(mod.modId);
+    }
+
+    @Override
+    public int hashCode() {
+        return modId.hashCode();
+    }
+
+    @Override
+    public int compareTo(Mod o) {
+        return this.modId.compareTo(o.modId);
+    }
+}