Graded polynomial identities on upper block triangular matrix algebras

Let G be an arbitrary abelian group. In the present paper we study the question of whether G-graded upper block triangular matrix algebras over a field of characteristic zero are determined, up to G-graded isomorphism, by their G-graded polynomial identities. We obtain some results for an elementary grading and, as a consequence, for any grading over an algebraically closed field.