  We study the transformations of the worldvolume fields of a system of
multiple coinciding D-branes under gauge transformations of the supergravity
Kalb-Ramond field. We find that the pure gauge part of these NS-NS
transformations can be written as a U(N) symmetry of the underlying Yang-Mills
group, but that in general the full NS-NS variations get mixed up non-trivially
with the U(N). We compute the commutation relations and the Jacobi identities
of the bigger group formed by the NS-NS and U(N) transformations.
