  The Schubert polynomials lift the Schur basis of symmetric polynomials into a
basis for Z[x1,x2,...]. We suggest the "prism tableau model" for these
polynomials. A novel aspect of this alternative to earlier results is that it
directly invokes semistandard tableaux; it does so as part of a colored tableau
amalgam. In the Grassmannian case, a prism tableau with colors ignored is a
semistandard Young tableau. Our arguments are developed from the Groebner
geometry of matrix Schubert varieties.
