  The gauge symmetries of a general dynamical system can be systematically
obtained following either a Hamiltonean or a Lagrangean approach. In the former
case, these symmetries are generated, according to Dirac's conjecture, by the
first class constraints. In the latter approach such local symmetries are
reflected in the existence of so called gauge identities. The connection
between the two becomes apparent, if one works with a first order Lagrangean
formulation. We thereby confirm Dirac's conjecture. Our analysis applies to
arbitrary constrained systems with first and second class constraints, and thus
extends a previous analysis by one of the authors to such general systems. We
illustrate our general results in terms of several examples.
