Something similar occurs in <fvLib> which currently has a model <zeroOrMore xmlns="http://relaxng.org/ns/structure/1.0"> <choice> <ref name="model.featureVal"/> </choice> </zeroOrMore> and in <classes> which currently is <choice xmlns="http://relaxng.org/ns/structure/1.0"> <zeroOrMore> <ref name="memberOf"/> </zeroOrMore> </choice> I'm regarding both of these as corrigible errors in the main P5 source and correcting them. But would appreciate feedback on the <langUsage> case.