  The algebraic structure of S-Theory and its representations are described.
This structure includes up to 13 hidden dimensions. It implies the existence of
an SO(10,2) covariant supergravity theory as a limit of the secret theory
behind string theory. The black hole entropy is invariant under transformations
including the 11th and 12th dimensions. The discussion includes generalization
into curved spacetime via various contractions of the superalgebras OSp(1/32),
OSp(1/64) etc..
