diff --git a/lattice2AttachablePlacement.py b/lattice2AttachablePlacement.py
index 6a31329..c503a07 100644
--- a/lattice2AttachablePlacement.py
+++ b/lattice2AttachablePlacement.py
@@ -130,12 +130,17 @@ class AttachedPlacementSubsequence(lattice2BaseFeature.LatticeFeature):
         created = self.assureProperty(selfobj, 
             'App::PropertyEnumeration', 
             'ReferencePlacementOption', 
-            ['origin', 'inherit', 'first placement', 'last placement'],
+            ['external', 'origin', 'inherit', 'first placement', 'last placement'],
             "Lattice Attached Placement Subsequence", 
             "Reference placement, corresponds to the original occurrence of the object to be populated. 'inherit' = use reference placement of the base attached placement."
         )
         if created:
             selfobj.ReferencePlacementOption = 'inherit'
+
+    def recomputeReferencePlm(self, selfobj, selfplacements): #override
+        if selfobj.ReferencePlacementOption == 'external':
+            super(AttachedPlacementSubsequence, self).recomputeReferencePlm(selfobj, selfplacements)
+        #the remaining options are handled in derivedExecute
     
     def derivedExecute(self,obj):
         attacher = Part.AttachEngine(screen(obj.Base).AttacherType)
@@ -157,7 +162,9 @@ class AttachedPlacementSubsequence(lattice2BaseFeature.LatticeFeature):
         
         #reference
         ref = obj.ReferencePlacementOption
-        if ref == 'origin':
+        if ref == 'external':
+            pass #gets done in recomputeReferencePlm
+        elif ref == 'origin':
             self.setReferencePlm(obj, None)
         elif ref == 'inherit':
             self.setReferencePlm(obj, lattice2BaseFeature.getReferencePlm(obj.Base))
diff --git a/lattice2LinearArray.py b/lattice2LinearArray.py
index 56258cd..020fc38 100644
--- a/lattice2LinearArray.py
+++ b/lattice2LinearArray.py
@@ -109,7 +109,7 @@ class LinearArray(lattice2BaseFeature.LatticeFeature):
         created = self.assureProperty(selfobj, 
             'App::PropertyEnumeration', 
             'ReferencePlacementOption', 
-            ['origin', 'SpanStart', 'SpanEnd', 'at custom value', 'first placement', 'last placement'],
+            ['external', 'origin', 'SpanStart', 'SpanEnd', 'at custom value', 'first placement', 'last placement'],
             "Lattice Array", 
             "Reference placement, corresponds to the original occurrence of the object to be populated."
         )
@@ -117,6 +117,11 @@ class LinearArray(lattice2BaseFeature.LatticeFeature):
             selfobj.ReferencePlacementOption = 'SpanStart'
         self.assureProperty(selfobj, 'App::PropertyDistance', 'ReferenceValue', 0.0, "Lattice Array", "Sets the value to use for generating ReferencePlacement. This value sets, what coordinate the object to be populated corresponds to.")
 
+    def recomputeReferencePlm(self, selfobj, selfplacements): #override
+        if selfobj.ReferencePlacementOption == 'external':
+            super(LinearArray, self).recomputeReferencePlm(selfobj, selfplacements)
+        #the remaining options are handled in derivedExecute
+        
     def derivedExecute(self,obj):
         self.assureGenerator(obj)
         self.updateReadonlyness(obj)
@@ -188,7 +193,9 @@ class LinearArray(lattice2BaseFeature.LatticeFeature):
 
         # update reference placement
         ref = obj.ReferencePlacementOption
-        if ref == 'origin':
+        if ref == 'external':
+            pass
+        elif ref == 'origin':
             self.setReferencePlm(obj, None)
         elif ref == 'SpanStart':
             self.setReferencePlm(obj, plmByVal(float(obj.SpanStart)))
diff --git a/lattice2PolarArray2.py b/lattice2PolarArray2.py
index cecd199..36fe2aa 100644
--- a/lattice2PolarArray2.py
+++ b/lattice2PolarArray2.py
@@ -93,7 +93,7 @@ class PolarArray(APlm.AttachableFeature):
         created = self.assureProperty(selfobj, 
             'App::PropertyEnumeration', 
             'ReferencePlacementOption', 
-            ['origin', 'center', 'SpanStart', 'SpanEnd', 'at custom value', 'first placement', 'last placement'],
+            ['external', 'origin', 'center', 'SpanStart', 'SpanEnd', 'at custom value', 'first placement', 'last placement'],
             "Polar Array", 
             "Reference placement, corresponds to the original occurrence of the object to be populated."
         )
@@ -129,6 +129,11 @@ class PolarArray(APlm.AttachableFeature):
             sub = sub[0]
             #resolve the link        
             return fetchArc(lnkobj, sub)
+            
+    def recomputeReferencePlm(self, selfobj, selfplacements): #override
+        if selfobj.ReferencePlacementOption == 'external':
+            super(PolarArray, self).recomputeReferencePlm(selfobj, selfplacements)
+        #the remaining options are handled in derivedExecute
         
     def derivedExecute(self,selfobj):
         self.assureGenerator(selfobj)
@@ -221,7 +226,9 @@ class PolarArray(APlm.AttachableFeature):
             
         # update reference placement
         ref = selfobj.ReferencePlacementOption
-        if ref == 'origin':
+        if ref == 'external':
+            pass #gets done in recomputeReferencePlm
+        elif ref == 'origin':
             self.setReferencePlm(selfobj, None)
         elif ref == 'center':
             self.setReferencePlm(selfobj, App.Placement())