[NTG-context] Additional typeface styles/alternatives with Selectfont

Dear List, I think Selectfont is great -- thank you, Wolfgang, for your work. However, I miss the features to define and use additional typeface styles and alternatives. Not everything fits in the predefined scheme of rm, ss, tt, hw, cg and mm, so it would be nice to have the possibility to define additional typeface styles. (I'm thinking for example about blackletter here.) It would also be nice if one could access arbitrary typeface alternatives, however the typeface creator has named them (e.g. something like semicondensed-ultrabold). At the moment, I think, it is only possible to map a few alternatives to the predefined switches. Kind regards, Joshua