--- /dev/null
+package iotcode.annotation;
+
+import java.lang.annotation.*;
+
+/** @constraint annotation
+ * This annotation is for the runtime system to instrument IoTSet and IoTRelation
+ *
+ * @author Rahmadi Trimananda <rahmadi.trimananda @ uci.edu>
+ * @version 1.0
+ * @since 2015-12-01
+ */
+@Retention(RetentionPolicy.RUNTIME)
+public @interface constraint {
+}