I created a product that adds new rules to structured text. To this aim I base a class on Structured Text and add to the rules of the base class like so: class DWIClass( StructuredText.DocumentWithImages.__class__ ): text_types = StructuredText.DocumentWithImages.text_types text_types.insert(1,'doc_named_linkEx' ) text_types.insert(1,'doc_inner_linkEx' ) text_types.insert(1,'doc_redPicture' ) My reasoning is that as text_types is a class variable it exists only once. However when I refresh the product after a change the above lines are added each time anew. Now my questions: Is my code wrong from a python view of things, or should refresh clear the whole thing? Does Python create an instance of the base class and an instance of my class?? Robert