ambiguous for taxon S ambiguous_for_taxon T if the class S does not have a clear referent in taxon T. An example would be the class 'manual digit 1', which encompasses a homology hypotheses that is accepted for some species (e.g. human and mouse), but does not have a clear referent in Aves - the referent is dependent on the hypothesis embraced, and also on the ontogenetic stage. [PHENOSCPAE:asilomar_mtg] taxonomic class assertion