  For a useful class of functions (containing functions whose one finite
component is essentially a matrix coefficient of a supercuspidal
representation), we establish three results about the unipotent contribution of
the Guo-Jacquet relative trace formula for the pair $(GL_n(D),GL_n(E))$. First
we get a fine expansion in terms of global nilpotent integrals. Second we
express these nilpotent integrals in terms of zeta integrals. Finally we prove
that they satisfy certain homogeneity properties. The proof is based on a new
kind of truncation introduced in a previous article.
