diff --git a/library/Businessprocess/Modification/NodeAction.php b/library/Businessprocess/Modification/NodeAction.php
index 98329bd..c895145 100644
--- a/library/Businessprocess/Modification/NodeAction.php
+++ b/library/Businessprocess/Modification/NodeAction.php
@@ -32,9 +32,11 @@ abstract class NodeAction
      *
      * @param Node|string $node
      */
-    public function __construct($node)
+    public function __construct($node = null)
     {
-        $this->nodeName = (string) $node;
+        if ($node !== null) {
+            $this->nodeName = (string) $node;
+        }
     }
 
     /**
@@ -63,6 +65,11 @@ abstract class NodeAction
         return $this->nodeName;
     }
 
+    public function hasNode()
+    {
+        return $this->nodeName !== null;
+    }
+
     /**
      * Whether this is an instance of a given action name
      *