  We describe a technique to derive constraints on the differential emission
measure (DEM) distribution, a measure of the temperature distribution, of
collisionally ionized hot plasmas from their X-ray emission line spectra. This
technique involves fitting spectra using a number of components, each of which
is the entire X-ray line emission spectrum for a single ion. It is applicable
to high-resolution X-ray spectra of any collisionally ionized plasma and
particularly useful for spectra in which the emission lines are broadened and
blended such as those of the winds of hot stars. This method does not require
that any explicit assumptions about the form of the DEM distribution be made
and is easily automated.
