diff --git a/core/api/src/main/java/org/onlab/onos/store/Timestamp.java b/core/api/src/main/java/org/onlab/onos/store/Timestamp.java
new file mode 100644
index 0000000..b9d3648
--- /dev/null
+++ b/core/api/src/main/java/org/onlab/onos/store/Timestamp.java
@@ -0,0 +1,8 @@
+package org.onlab.onos.store;
+
+/**
+ * Opaque version structure.
+ */
+public interface Timestamp extends Comparable<Timestamp> {
+
+}