This description was provided by N. Guex for Swiss-PdbViewer version 1.0
in December 1995.

The short-term purpose is to develop a multi-platform (MAC, PC, UNIX)
modeling package that will directly submit modeling requests to
the SWISS-model server (http://expasy.hcuge.ch/swissmod/SWISS-MODEL.html).

Several proteins can be analyzed at the same time and can be
"piled-up" in 3D space by picking 3 corresponding reference
atoms of the structures to align. RMS can be calculated on
selected amino acids of the aligned proteins, taking into account
alpha carbon only (CA), backbone atoms only or the whole
amino-acids atoms. The comparison of active sites and other relevant
parts are therefore very easy. SWISS-PdbViewer can also measure angles
and distances between atoms as well as add/remove amino acids to/from
the view with simple mouse clicks thanks to the intuitive graphic and
menu driven interface.

A control Panel regroups all the most frequently used display
facilities so that atom types and names (according to Weiner et al.
(1984), J. Am. Chem. Soc. 106, 765-784), sidechain display/undisplay
and amino acid color are accessible with a single click. H-bonds can
be estimated for the whole molecule even if the PDB file does not
provide explicit H atoms, and it is possible to mutate amino acids
sidechains by browsing a rotamer library. During the mutation process,
H-bonds and steric hindrances are automatically estimated and
displayed in real time, facilitating the best rotamer choice.