  We study the boundary asymptotics of ACH metrics which are formally Einstein.
In terms of the partially integrable almost CR structure induced on the
boundary at infinity, existence and uniqueness of such formal asymptotic
expansions are studied. It is shown that there always exist formal solutions to
the Einstein equation if we allow logarithmic terms, and that a local
CR-invariant tensor arises as the obstruction to the existence of a log-free
solution. Some properties of this new CR invariant, the CR obstruction tensor,
are discussed.
