  A number of emission and absorption features are expected to be visible in
high energy resolution X-ray spectra of type 1 AGN with ionized gas along the
line of sight (so called "warm absorbers"). Emission strongly depends on the
geometrical configuration of the gas, while absorption along the line of sight
does not. Absorption features include photoelectric absorption K and L edges
along with many strong K$\alpha$, K$\beta$ and L resonance absorption lines
from the most abundant elements. We present detailed simulations of our
``photoelectric + resonant absorption'' model with the high energy resolution
gratings and calorimeters of AXAF, XMM and Constellation-X, and discuss the
relevant physics which can be addressed with the new generation of X-ray
spectrometers.

Astrophysics