  The equations of motion of the massless sector of the two dimensional string
theory, obtained by compactifying the heterotic string theory on an eight
dimensional torus, is known to have an affine o(8,24) symmetry algebra
generating an O(8,24) loop group. In this paper we study how various known
discrete S- and T- duality symmetries of the theory are embedded in this loop
group. This allows us to identify the generators of the discrete duality
symmetry group of the two dimensional string theory.
