Given a finitely generated algebra A and a natural number d, we descri
be explicitely a decomposition of the variety of all d-dimensional A-m
odules into finitely many locally closed Gl(d)- stable subvarieties an
d we give on each of these subvarieties a finite number of Gl(d)-invar
iant regular functions that separate the orbits. Unfortunately this de
composition is very hard to compute.