BPS States in 10+2 Dimensions

We discuss a (10+2)D N=(1,1) superalgebra and its projections to M-theory, type IIA and IIB algebras. From the complete classification of a second-rank central term valued in the so(10,2) algebra, we find all possible BPS states coming from this term. We show that, among them, there are two types of 1/2-susy BPS configurations; one corresponds to a super (2+2)-brane while another one arises from a nilpotent element in so(10,2).