Restricted Supergauge invariance, N=2 Coadjoint Orbit and N=2 Quantum   Supergravity
  It is shown that the N=2 superconformal transformations are restricted N=1 supergauge transformations of a supergauge theory with Osp(2,2) as a gauge group. Based on this result, a canonical derivation of the Osp(2,2) current algebra in the superchiral gauge formulation of N=2 supergravity is presented. 
W.A. Sabra