diff --git a/README.md b/README.md
index f1081ce..079d519 100644
--- a/README.md
+++ b/README.md
@@ -116,15 +116,15 @@
 
 ## handle unavailable items
 
-Set the following items "unavailable" (need to specify complete list each time when this list is changed):
+Set the following items as unavailable (need to specify complete list each time when this list is changed):
 
 ```
 curl -i -X POST http://localhost:7070/events.json?accessKey=zPkr6sBwQoBwBjVHK2hsF9u26L38ARSe19QzkdYentuomCtYSuH0vXP5fq7advo4 \
 -H "Content-Type: application/json" \
 -d '{
   "event" : "$set",
-  "entityType" : "itemConstraint"
-  "entityId" : "unavailable",
+  "entityType" : "constraint"
+  "entityId" : "unavailableItems",
   "properties" : {
     "items": ["i43", "i20", "i37", "i3", "i4", "i5"],
   }
@@ -132,15 +132,15 @@
 }'
 ```
 
-No more items "unavailable":
+Set empty list when no more items unavailable:
 
 ```
 curl -i -X POST http://localhost:7070/events.json?accessKey=zPkr6sBwQoBwBjVHK2hsF9u26L38ARSe19QzkdYentuomCtYSuH0vXP5fq7advo4 \
 -H "Content-Type: application/json" \
 -d '{
   "event" : "$set",
-  "entityType" : "itemConstraint"
-  "entityId" : "unavailable",
+  "entityType" : "constraint"
+  "entityId" : "unavailableItems",
   "properties" : {
     "items": [],
   }
diff --git a/src/main/scala/ALSAlgorithm.scala b/src/main/scala/ALSAlgorithm.scala
index 73ffa87..e01d31d 100644
--- a/src/main/scala/ALSAlgorithm.scala
+++ b/src/main/scala/ALSAlgorithm.scala
@@ -185,11 +185,11 @@
       Set[String]()
     }
 
-    // get the latest itemConstraint unavailable $set event
+    // get the latest constraint unavailableItems $set event
     val unavailableItems: Set[String] = lEventsDb.findSingleEntity(
       appId = ap.appId,
-      entityType = "itemConstraint",
-      entityId = "unavailable",
+      entityType = "constraint",
+      entityId = "unavailableItems",
       eventNames = Some(Seq("$set")),
       limit = Some(1),
       latest = true,
@@ -203,7 +203,7 @@
         }
       }
       case Left(e) => {
-        logger.error(s"Error when read unavailable items: ${e}")
+        logger.error(s"Error when read set unavailableItems event: ${e}")
         Set[String]()
       }
     }