  We present a detailed study of the observable effects of photoionization and
Comptonization of line and continuum radiation from a cold accretion disk with
a thin, warm, photoionized transition layer in the framework of self-consistent
accretion-disk corona models for Galactic black-hole candidates. We use an
iterative method to treat the non-linear radiation feedback between the
transition layer and the hot corona numerically using a Monte-Carlo
Comptonization code in combination with the photoionization and line transfer
code XSTAR. The subset of the parameter space allowed in self-consistent
accretion-disk corona systems on energetic grounds is explored, checking for
the emergence of emission lines and/or absorption edges, with special emphasis
on the spectral range $E \lesssim 1$ keV where such features might become
observable with the advent of the AXAF satellite. Comparing our model
calculations to the broadband spectrum of GX~339-4, we find good agreement with
the observed spectral features and discuss how the future detection of the
predicted features at lower energies can be used to constrain parameters.
