  The influence of a magnetic field on the broadening of spectral lines and
transition arrays in complex spectra is investigated. The anomalous absorption
or emission Zeeman pattern is a superposition of many profiles with different
relative strengths, shifts, widths, asymmetries and sharpnesses. The "sigma"
and "pi" profiles can be described statistically, using the moments of the
Zeeman components. We present two statistical modellings: the first one
provides a diagnostic of the magnetic field and the second one can be used to
include the effect of a magnetic field on simulated atomic spectra in an
approximate way.
