  We present results of the photoionization code IRIS, which calculates the
spectrum emitted by the Warm Absorber (WA) in Seyfert 1 galaxies for a large
grid of parameters (density, column density, ionization parameter...). We show
that in Seyfert 1s, coronal lines Fe X, Fe XI, Fe XIV...), whose emission
region shares common characteristics with the WA, could be formed in the WA.
Unlike the absorption edges, such as those of O VII and O VIII observed in soft
X-rays which are produced by the WA, these lines strongly constrain the
physical parameters of the WA, especially the hydrogen density. Indeed, in
order to avoid producing coronal line equivalent widths larger than observed, a
high density (nH \geq 10^{10} cm-3) is required for the WA in most cases. This
result is obtained for the mean observed Seyfert 1 features, as well as for the
case study of MCG-6-30-15. It implies that the distance of the WA from the
incident radiation source is of the order of that of the Broad Line Region
(BLR)
