[NTG-context] bibmodule question

I'm trying to have the edition of a book typeset as a superscript, small number. In my setuppublicationlayout[book], I tried this: \insertedition{ \high\bgroup\tfxx}{\egroup}{ }% which seemed like a good idea when I wrote it, but it isn't working; I get the number in tiny font size, but it isn't raised. Any suggestions would be appreciated. Thomas