In the BridgePoint help see: BridgePoint UML Suite Help > Reference > Using BridgePoint > xtUML Modeling Perspective > Model Elements > Data Types
I did a quick search in the public https://github.com/xtuml/models repository for the word “sender”. Then browsed to find “.xtuml” files in the search results. I see at least the VerifierMessageTestGlobals and ComponentSyntaxTest models both contain uses of “sender” and the component_ref data type. I suggest you import the ComponentSyntaxTest model and see how it uses “sender”.