Question about require/provide/obsolete

Are provide/require/obsolete fields allowed to contain non-numeric
characters other than '-'? For example, can an rpm require something
with version 2.4-1fr instead of just 2.4-1?

I'm working on adjusting Fedora Tracker so it stores this info and would
like to be able to display, eg, the requires for a package such that
each require is a link. When clicked, the link would initiate a search
that returns packages whose provides meet the requirement. Needless to
say, such a search will be a lot easier if I can split the "version"
into two int fields.

Suggestions?
--Brad