  The metric recommanded by the IAU2000 resolutions allows propagation of light
calculations at the c-3 level in the general relativity framework. In a recent
paper [1], motivated by forthcoming space experiments involving propagation of
light in the Solar System (ASTROD, GAIA, LATOR, ODYSSEY, SAGAS, SIM, TIPO,
...), we have proposed an extention of the IAU metric equations at the c-4
level. This has been made in the general relativity framework. However,
scalar-tensor theories may induce corrections numerically comparable to the c-4
general relativistic terms. Accordingly, one proposes in this paper an
extension of [1] to the scalar-tensor case. The case of a strongly hierarchized
system (such as the Solar system) is emphasized. In this case, an explicit
metric solution is proposed.
