  We give a bijective proof of an identity relating primed shifted
gl(n)-standard tableaux to the product of a gl(n) character in the form of a
Schur function and a product of sums of x and y terms. This result generalises
a number of well--known results due to Robbins and Rumsey, Chapman, Tokuyama,
Okada and Macdonald. An analogous result is then obtained in the case of primed
shifted sp(2n)-standard tableaux which are bijectively related to the product
of a t-deformed sp(2n) character and another x and y product. All results are
also interpreted in terms of alternating sign matrix identities, including a
result regarding subsets of ASMs specified by conditions on certain restricted
column sums.
