It is essential to compare
spatial- and time-resolved spectral observations
to flare model predictions, in order to understand the
geometry of the events and to test the various
theoretical models that have been put forward in the last decades.
The relation between the structures as seen in the higher corona and those
at lower heights, in the transition region and chromosphere, can
be studied with CDS.
The potential of the CDS instrument is fully exploited when plasma
diagnostic techniques are applyed
to determine the plasma
characteristics (temperatures, densities, velocities,
chemical abundances) across an active region.
