diff --git a/framework/src/main/java/org/toop/framework/eventbus/events/ResponseToUniqueEvent.java b/framework/src/main/java/org/toop/framework/eventbus/events/ResponseToUniqueEvent.java
index 30328ce..6f65378 100644
--- a/framework/src/main/java/org/toop/framework/eventbus/events/ResponseToUniqueEvent.java
+++ b/framework/src/main/java/org/toop/framework/eventbus/events/ResponseToUniqueEvent.java
@@ -4,6 +4,17 @@ import java.lang.reflect.RecordComponent;
 import java.util.HashMap;
 import java.util.Map;
 
+/**
+ * MUST HAVE long identifier at the end.
+ * e.g.
+ *
+ * <pre>{@code
+ * public record uniqueEventResponse(String content, long identifier) implements ResponseToUniqueEvent {};
+ * public record uniqueEventResponse(long identifier) implements ResponseToUniqueEvent {};
+ * public record uniqueEventResponse(String content, int number, long identifier) implements ResponseToUniqueEvent {};
+ * }</pre>
+ *
+ */
 public interface ResponseToUniqueEvent extends UniqueEvent {
     default Map<String, Object> result() {
         Map<String, Object> map = new HashMap<>();
diff --git a/framework/src/main/java/org/toop/framework/eventbus/events/UniqueEvent.java b/framework/src/main/java/org/toop/framework/eventbus/events/UniqueEvent.java
index bb68f61..6042c83 100644
--- a/framework/src/main/java/org/toop/framework/eventbus/events/UniqueEvent.java
+++ b/framework/src/main/java/org/toop/framework/eventbus/events/UniqueEvent.java
@@ -1,5 +1,16 @@
 package org.toop.framework.eventbus.events;
 
+/**
+ * MUST HAVE long identifier at the end.
+ * e.g.
+ *
+ * <pre>{@code
+ * public record uniqueEvent(String content, long identifier) implements UniqueEvent {};
+ * public record uniqueEvent(long identifier) implements UniqueEvent {};
+ * public record uniqueEvent(String content, int number, long identifier) implements UniqueEvent {};
+ * }</pre>
+ *
+ */
 public interface UniqueEvent extends EventType {
     default long getIdentifier() {
         try {