We discuss T-duality for open strings in general background fields both in
the functional integral formulation as well as in the language of canonical
transformations. The Dirichlet boundary condition in the dual theory has to be
treated as a constraint on the functional integration. Furthermore, we give
meaning to the notion of matrix valued string end point position in the
presence of nonabelian gauge field background.Comment: 10 pages, Latex, an inconsistency of the notation in section 3 is
removed, 2 references adde