IIB Supergravity Revisited
  We show in the SU(1,1)-covariant formulation that IIB supergravity allows the introduction of a doublet and a quadruplet of ten-form potentials. The Ramond-Ramond ten-form potential which is associated with the SO(32) Type I superstring is in the quadruplet. Our results are consistent with a recently proposed $E_{11}$ symmetry underlying string theory. For the reader's convenience we present the full supersymmetry and gauge transformations of {\it all} fields both in the manifestly SU(1,1) covariant Einstein frame and in the real U(1) gauge fixed string frame. 
Eric A. Bergshoeff, Mees de Roo, Sven F. Kerstan, Fabio Riccioni