Unusual gauded supergravities from type IIA and type IIB orientifolds

We analyse different N = 4 supergravities coupled to six vector multiplets corresponding to low-energy descriptions of the bulk sector of T-6/Z(2) orientifolds with p-brane in IIB (p odd) and in IIA (p even) superstrings. When fluxes are turned on, a gauging emerges corresponding to some non-semisimple Lie algebra related to nilpotent subalgebras N-p subset of so(6, 6), with dimension h(Np) = 15 + (p - 3)(9 - p). The non-metric axions have Stueckelberg couplings that induce a spontaneous breaking of gauge symmetries. In four cases the gauge algebra is non-Abelian with a non-commutative structure of the compactification torus. due to fluxes of NS-NS and R-R forms