diff --git a/core/api/src/main/java/org/onlab/onos/mastership/MastershipEvent.java b/core/api/src/main/java/org/onlab/onos/mastership/MastershipEvent.java
index 60f0dad..5447545 100644
--- a/core/api/src/main/java/org/onlab/onos/mastership/MastershipEvent.java
+++ b/core/api/src/main/java/org/onlab/onos/mastership/MastershipEvent.java
@@ -40,7 +40,9 @@
         MASTER_CHANGED,
 
         /**
-         * Signifies that the list of backup nodes has changed.
+         * Signifies that the list of backup nodes has changed. If
+         * the change in the backups list is accompanied by a change in
+         * master, the event is subsumed by MASTER_CHANGED.
          */
         BACKUPS_CHANGED
     }