diff --git a/jsprit-core/src/main/java/jsprit/core/problem/solution/route/state/StateFactory.java b/jsprit-core/src/main/java/jsprit/core/problem/solution/route/state/StateFactory.java
index 5b591e12..e5945cb7 100644
--- a/jsprit-core/src/main/java/jsprit/core/problem/solution/route/state/StateFactory.java
+++ b/jsprit-core/src/main/java/jsprit/core/problem/solution/route/state/StateFactory.java
@@ -27,9 +27,8 @@ import java.util.Map;
 
 
 public class StateFactory {
-	
-	
-	public interface StateId {
+
+    public interface StateId {
 		
 	}
 	
@@ -77,6 +76,8 @@ public class StateFactory {
 		}
 
 	}
+
+    public static final StateId SKILLS = new StateIdImpl("skills");
 	
 	public final static StateId MAXLOAD = new StateIdImpl("maxload");