BPS preons and tensionless super-p-branes in generalized superspace

Tensionless super-p-branes in a generalized superspace with additional tensorial central charge coordinates may provide an extended object model for BPS preons, i.e., for the hypothetical constituents of M-theory preserving 31 of 32 supersymmetries [I.A. Bandos, J.A. de Azcárraga, J.M. Izquierdo, J. Lukierski, Phys. Rev. Lett. 86 (2001) 4451].