XPM (X PixMap) is a format for storing/retrieving X pixmaps to/from files.
A website for XPM is available at
http://koala.ilog.fr/lehors/xpm.html.
XPM can be downloaded from
ftp://ftp.x.org/contrib/libraries/
or from
http://koala.ilog.fr/ftp/pub/xpm/.
XPM is not a GNU program.