  With a view toward the problem of computing the linearized cosmological
perturbations in Randall-Sundrum cosmological models where a Z2 symmetry has
been imposed about a boundary brane, we derive the form of the linearized
Israel matching conditions and the auxiliary gauge conditions on the boundary
when Lorentz gauge has been imposed in the bulk. This gauge is completely
covariant and local, manifestly respecting all the AdS5 symmetries in the bulk
and not relying on a decomposition into pure scalar, vector, and tensor
sectors, which is necessarily nonlocal. We demonstrate that the auxiliary gauge
conditions on the boundary ensure that bulk gravitons upon reflection off the
brane do not emit polarizations that violate the bulk Lorentz gauge condition.
We also characterize the residual gauge freedom, embodied by five longitudinal
(pure gauge) graviton polarizations in the bulk, four of which correspond to
reparameterizations of the induced brane metric and one of which corresponds to
normal displacements of the brane.
