diff --git a/QvtoTransformationRules/transforms/ClassDiagram/Operations.qvto b/QvtoTransformationRules/transforms/ClassDiagram/Operations.qvto
index 8876c32..fceaf95 100644
--- a/QvtoTransformationRules/transforms/ClassDiagram/Operations.qvto
+++ b/QvtoTransformationRules/transforms/ClassDiagram/Operations.qvto
@@ -6,8 +6,6 @@ modeltype UML uses 'http://www.eclipse.org/uml2/5.0.0/UML';
 modeltype OPCUA uses set('http://opcfoundation.org/UA/2011/03/UANodeSet.xsd');
 modeltype TYPES uses types('http://opcfoundation.org/UA/2008/02/Types.xsd');
 modeltype ecore "strict" uses 'http://www.eclipse.org/emf/2002/Ecore';
-modeltype UMLTYPES uses types('http://www.eclipse.org/uml2/5.0.0/Types');
-modeltype UMLPARAMETER uses umlParameter('http://www.eclipse.org/papyrus/uml/textedit/parameter/xtext/UmlParameter');
 
 /*
  * Transforming UML Operations to OPC UA Methods requires an UAMethod node and, possibly,
@@ -37,7 +35,7 @@ mapping UML::Operation::operation2UAMethod(inout parent : OPCUA::UANode, inout n
 	if (self.ownedElement->selectByType(UML::Parameter)->select(direction = UML::ParameterDirectionKind::_'in')->size() > 0){ // if the operation has input parameters
 		// create a UAVariable for input arguments
 		var inputArgumentsVariable := object OPCUA::UAVariable{
-			nodeId := self.createNodeId() + "InputArguments";
+			nodeId := self.createNodeId(false);
 			browseName := "InputArguments";
 			displayName := object OPCUA::LocalizedText{value := "InputArguments"};
 			dataType := getIdOrAlias("Argument");
@@ -72,7 +70,7 @@ mapping UML::Operation::operation2UAMethod(inout parent : OPCUA::UANode, inout n
 	if (self.ownedElement->selectByType(UML::Parameter)->select(direction = UML::ParameterDirectionKind::_'out')->size() > 0){ // if the operation has output parameters
 		// create a UAVariable for output arguments
 		var outputArgumentsVariable := object OPCUA::UAVariable{
-			nodeId := self.createNodeId() + "OutputArguments";
+			nodeId := self.createNodeId(false);
 			browseName := "OutputArguments";
 			displayName := object OPCUA::LocalizedText{value := "OutputArguments"};
 			dataType := "Argument";
diff --git a/QvtoTransformationRules/transforms/ClassDiagram/References.qvto b/QvtoTransformationRules/transforms/ClassDiagram/References.qvto
index fa43420..302bb45 100644
--- a/QvtoTransformationRules/transforms/ClassDiagram/References.qvto
+++ b/QvtoTransformationRules/transforms/ClassDiagram/References.qvto
@@ -43,7 +43,7 @@ mapping UML::Property::property2Reference(inout parent : OPCUA::UANode, inout no
 			};
 			
 			var targetObject := object OPCUA::UAObject{
-				nodeId := self.createNodeId(targetObjectName);
+				nodeId := self.createNodeId(false);
 				parentNodeId := parent.nodeId;
 			};
 			
@@ -94,7 +94,7 @@ mapping UML::Property::property2Reference(inout parent : OPCUA::UANode, inout no
 			
 			log("Creating new reference type " + self.association.name);
 			var newReferenceType := object OPCUA::UAReferenceType {
-				nodeId := self.createNodeId(self.association.name);
+				nodeId := self.association.createNodeId();
 				browseName := self.association.name;
 				displayName := object OPCUA::LocalizedText{value := self.association.name};
 			};
diff --git a/QvtoTransformationRules/transforms/Common/Helpers.qvto b/QvtoTransformationRules/transforms/Common/Helpers.qvto
index 71b1587..69db55d 100644
--- a/QvtoTransformationRules/transforms/Common/Helpers.qvto
+++ b/QvtoTransformationRules/transforms/Common/Helpers.qvto
@@ -14,6 +14,9 @@ modeltype OPCUA uses set('http://opcfoundation.org/UA/2011/03/UANodeSet.xsd');
 // identifier have the form i=256
 // nodeIds have the form ns=2;s=someString
 
+property nodeIdCount : Integer = 1000;
+property nodeIdLookupTable : Dict(UML::Element, String); // used to ensure that a nodeId is reused if it is generated for the same UML::Element twice
+
 // entries are of the form "http://opcfoundation.org/UA/","NonHierarchicalReferences","i=32"
 property IdentifierLookupTable : Dict(String,Dict(String,String)); 
 
@@ -65,9 +68,9 @@ helper UML::Element::getUri() : String {
 	return uri;
 }
 
-helper UML::NamedElement::getNodeIdPrefix() : String {
+helper UML::Element::getNodeIdPrefix() : String {
 	var ns := self.getUri();
-	return "ns=" + NamespaceUri2NamespaceIndex->get(ns).toString() + ";s=";
+	return "ns=" + NamespaceUri2NamespaceIndex->get(ns).toString() + ";i=";
 }
 
 helper UML::NamedElement::getNamePostfix() : String {
@@ -78,14 +81,32 @@ helper UML::NamedElement::getNamePostfix() : String {
 	};
 }
 
-helper UML::NamedElement::createNodeId() : String {
-	return self.getNodeIdPrefix() + self.name + self.getNamePostfix();
+helper UML::Element::createNodeId() : String {
+	// check if there has already been generated a nodeId for this UML::Element and if so, reuse that node id;
+	var nodeId := "";
+	if(nodeIdLookupTable->keys()->includes(self)) {
+		nodeId := nodeIdLookupTable->get(self);
+	} else {
+		nodeId := self.getNodeIdPrefix() + nodeIdCount.toString();
+		nodeIdLookupTable->put(self, nodeId);
+		nodeIdCount := nodeIdCount + 1;
+	};
+	return nodeId;
 }
 
-helper UML::NamedElement::createNodeId(nodeName : String) : String {
-	return self.getNodeIdPrefix() + nodeName + self.getNamePostfix();
+helper UML::Element::createNodeId(canReuseExistingNode : Boolean) : String {
+	var nodeId := "";
+	if(canReuseExistingNode) {
+		nodeId := self.createNodeId();
+	} else {
+		nodeId := self.getNodeIdPrefix() + nodeIdCount.toString();
+		nodeIdLookupTable->put(self, nodeId);
+		nodeIdCount := nodeIdCount + 1;
+	};
+	return nodeId;
 }
 
+
 helper UML::NamedElement::createBrowseName() : String {
 	return self.name + self.getNamePostfix();
 }
@@ -119,6 +140,7 @@ helper loadInternalNodeIds() {
 	y->put("String", "i=12");
 	y->put("LocalizedText", "i=21");
 	y->put("NonHierarchicalReferences", "i=32");
+	y->put("Organizes", "i=35");
 	y->put("HasModellingRule", "i=37");
 	y->put("HasTypeDefinition", "i=40");
 	y->put("HasSubtype", "i=45");
@@ -133,6 +155,7 @@ helper loadInternalNodeIds() {
 	y->put("PropertyType", "i=68");
 	y->put("ModellingRule_Mandatory", "i=78");
 	y->put("ModellingRule_Optional", "i=80");
+	y->put("ObjectsFolder", "i=85");
 	y->put("HasSubStateMachine", "i=117");
 	y->put("ModellingRule_OptionalPlaceholder", "i=11508");
 	y->put("ModellingRule_MandatoryPlaceholder", "i=11510");
diff --git a/QvtoTransformationRules/transforms/StateMachineDiagram/Transitions.qvto b/QvtoTransformationRules/transforms/StateMachineDiagram/Transitions.qvto
index 3bc7cea..062938d 100644
--- a/QvtoTransformationRules/transforms/StateMachineDiagram/Transitions.qvto
+++ b/QvtoTransformationRules/transforms/StateMachineDiagram/Transitions.qvto
@@ -21,7 +21,7 @@ mapping UML::Transition::transition2Transition(inout nodeset : OPCUA::UANodeSetT
 
 	// set attributes of the OPCUA::UAObjectType
 	browseName := transitionName;
-	nodeId := self.createNodeId(transitionName);
+	nodeId := self.createNodeId();
 	displayName := displayName := object OPCUA::LocalizedText{value := browseName};
 	parentNodeId := parent.nodeId;