C**D -- the tensor product of two chain complexes.
The result,
E, is a chain complex. Each module
E_k in it is a direct sum of modules of the form
C_i**D_j with
i+j=k, and the preferred keys for the components of this direct sum are the pairs
(i,j), sorted increasing values of
i. For information about how to use preferred keys, see
directSum.