  We study the Borel reducibility of isomorphism relations in the generalized
Baire space $\kappa^\kappa$. In the main result we show for inaccessible
$\kappa$, that if $T$ is a classifiable theory and $T'$ is stable with OCP,
then the isomorphism of models of $T$ is Borel reducible to the isomorphism of
models of $T'$.
