UMLR — ExpansionNodes owned by ExpansionRegions?

Are ExpansionNodes owned by their ExpansionRegions? ENs are pin-like, so it seems like they should be, but then I would have expected ER::in/outputElement and EN::regionAsIn/Output to be subsetted from StructuredActivityNode::node and ActivityNode::inStructuredNode, respectively. ENs could still be owned by ERs as SANs without the subsetting, but I couldn't find what the spec says about it. Is there a MIWG test for this case?

Ed S's response:http://www.omg.org/archives/model-interchange/msg02614.html