923 

   923 In this subsection we define an $n{+}1$-category of ``sphere modules" whose objects

   924 

   924 correspond to $n$-categories.

   925 Outline:

   925 This is a version of the familiar algebras-bimodules-intertwinors 2-category.

   926 \begin{itemize}

   926 (Terminology: It is clearly appropriate to call an $S^0$ modules a bimodule,

   927 \item 

   927 since a 0-sphere has an obvious bi-ness.

   928 \end{itemize}

   928 This is much less true for higher dimensional spheres, 

   929 so we prefer the term ``sphere module" for the general case.)

   930