In this paper we study the map associating to a linear differential operator
with rational coefficients its monodromy data. The operator has one regular and
one irregular singularity of Poincare' rank 1. We compute the Poisson structure
of the corresponding Monodromy Preserving Deformation Equations on the space of
the monodromy data.Comment: 16 pages,Tex,to be published in IMR
