Threebranes in twelve dimensions
  In this note we discuss the theory of super-threebranes in a spacetime of signature (10,2). Upon reduction, the threebrane provides us with the classical representations of the M-2-brane and the type IIB superstring. Many features of the original super (2+2)-brane theory are clarified. In particular, the (10,2) superspace and the spinors required to construct the brane action are discussed. 
Stephen F. Hewson