  In this paper we fill some gaps in the arguments of our previous papers
[hep-th/9412229,hep-th/9604044]. In particular, we give a proof that the L
operators of Conformal Field Theory indeed satisfy the defining relations of
the Yang-Baxter algebra. Among other results we present a derivation of the
functional relations satisfied by ${\bf T}$ and ${\bf Q}$ operators and a proof
of the basic analyticity assumptions for these operators used in
[hep-th/9412229,hep-th/9604044].
