  Let O be a complete discrete valuation domain with finite residue field. In
this paper we describe the irreducible representations of the groups Aut(M) for
any finite O-module M of rank two. The main emphasis is on the interaction
between the different groups and their representations. An induction scheme is
developed in order to study the whole family of these groups coherently. The
results obtained depend on the ring O in a very weak manner, mainly through the
degree of the residue field. In particular, a uniform description of the
irreducible representations of GL(2,O/P^k) is obtained, where P is the maximal
ideal of O.
