  Semantic Heterogeneity is conventionally understood as the existence of
variance in the representation of a target reality when modelled, by
independent parties, in different databases, schemas and/ or data. We argue
that the mere encoding of variance, while being necessary, is not sufficient
enough to deal with the problem of representational heterogeneity, given that
it is also necessary to encode the unifying basis on which such variance is
manifested. To that end, this paper introduces a notion of Representation
Heterogeneity in terms of the co-occurrent notions of Representation Unity and
Representation Diversity. We have representation unity when two heterogeneous
representations model the same target reality, representation diversity
otherwise. In turn, this paper also highlights how these two notions get
instantiated across the two layers of any representation, i.e., Language and
Knowledge.
