--- a/src/main/java/de/mpiwg/itgroup/annotations/Annotation.java	Fri Feb 10 15:02:32 2017 +0100
+++ b/src/main/java/de/mpiwg/itgroup/annotations/Annotation.java	Fri Feb 10 15:45:35 2017 +0100
@@ -131,6 +131,13 @@
     protected Set<String> tags;
     
     /**
+     * Enum of actions (for permissions).
+     */
+    public static enum Action {
+    	read, update, create, delete, admin
+    }
+    
+    /**
      * Returns if the requested action is allowed for the given user on this annotation.
      * 
      * @param action
@@ -138,8 +145,8 @@
      * @param store AnnotationStore to check group membership
      * @return
      */
-    public boolean isActionAllowed(String action, Person user, AnnotationStore store) {
-        if (action.equals("read")) {
+    public boolean isActionAllowed(Action action, Person user, AnnotationStore store) {
+        if (action == Action.read) {
             Actor reader = getReadPermission();
             if (reader == null) {
                 // if not specified then everybody is allowed
@@ -147,7 +154,7 @@
             } else {
                 return reader.isEquivalentWith(user, store);
             }
-        } else if (action.equals("update")) {
+        } else if (action == Action.update) {
             // require at least an authenticated user
             if (user == null) return false;
             Actor updater = getUpdatePermission();
@@ -157,7 +164,7 @@
             } else {
                 return updater.isEquivalentWith(user, store);
             }
-        } else if (action.equals("delete")) {
+        } else if (action == Action.delete) {
             // require at least an authenticated user
             if (user == null) return false;
             Actor deleter = getDeletePermission();
@@ -166,7 +173,7 @@
                 deleter = creator;
             }
             return deleter.isEquivalentWith(user, store);
-        } else if (action.equals("admin")) {
+        } else if (action == Action.admin) {
             // require at least an authenticated user
             if (user == null) return false;
             Actor admin = getAdminPermission();