We classify the operator content of local hermitian scalar operators in the
Sinh-Gordon model by means of independent solutions of the form-factor
bootstrap equations. The corresponding linear space is organized into a
tower-like structure of dimension n for the form factors F2nβ and
F2nβ1β. Analyzing the cluster property of the form factors, a particular
class of these solutions can be identified with the matrix elements of the
operators ekgΟ. We also present the complete expression of the form
factors of the elementary field Ο(x) and the trace of the energy-momentum
tensor Ξ(x).Comment: ISAS/EP/93/42, to appear in Phys. Lett.