  This paper discusses the properties of scattering--dominated active galactic
nuclei (AGN). We define these to be AGN for which the direct line-of-sight to
the continuum source is obscured by Compton-thick material. The aim is to
construct, for the first time, a model consistent with X-ray line luminosities,
line ratios and various luminosity indicators. The ASCA spectra of six such
sources show several X-ray lines that can be reliably measured, mostly due to
highly ionized magnesium, silicon sulphur and iron. These enable us to
investigate the physical conditions of the scattering material. The sources
show evidence of He-like and H-like iron lines that are likely to be produced
in hot (T approx 10^6 K) photoionized gas. By measuring the EW of the lines,
and by constructing a diagnostic line-ratio diagram, we demonstrate that the
silicon and magnesium lines are produced by the same gas emitting the highly
ionized iron lines. The properties of this gas are rather different from the
properties of warm absorbers in type I AGN. Neutral 6.4 keV iron lines are also
detected, originating in a different component which can be either Compton-thin
or Compton-thick. The best measured iron lines suggest an enhancement of
n_{Fe}/n_H by a factor approx 2 compared to solar, in both the hot and cool
Compton-thin components. We further show that in four of the sources, the Fe
Kalpha(6.4keV)/Hbeta (lambda 4861Ang) line ratio is consistent with that
predicted for typical narrow line region clouds, and the reddening corrected
Hbeta is known, provided the column density is larger than approx
10^{22.5}/cm^2, alpha_{ox} is smaller than 1.3. For some sources, this is a
viable alternative to the commonly assumed Compton thick medium as the origin
of the 6.4 keV iron line.
