[tei-council] alternate to what?

aka: class system bites us again? The <model>, <modelGrp>, and <modelSequence> elements allow <altIdent> as a child (via model.glossLike), but since the do not have an @ident attribute, what is <altIdent> supposed to be an alternate to? (The same is true for <taxonomy>, but since it is not in the 'tagdocs' module, it seems like less of a problem.)