  Berkovits and Vafa recently showed that critical string theories can be
considered as critical superstring theories with a special choice of
background. The embedding of the Virasoro algebra into the super-Virasoro
algebra involved in this construction has been extended to the noncritical case
by Berkovits and Ohta. It is shown that the resulting nonlinear realization of
the super-Virasoro algebra can be interpreted using standard techniques from
the theory of nonlinear realizations. This extends earlier work of Kunitomo.
