StdProp for UML attributes?

[Andrew S Halper <ashalper acm org>]

I'm attempting to write the StdProp code for the UML attributes, and I
was wondering what the appropriate property type should be?  At first I
thought ListProperty (defined in lib/prop_widgets.h), but now I think
that might not be what I want.  Is there an available property type I
should use, or is it necessary to invent one?

Thanks,
Andy