These are the graphics of the Cuyo level Plane
Citing the metadata of that level:
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
Comments
I've come across this set a few times now.
What file type is this and how do you use it?
Accidental double post
In a nutshell, xpm is an image format for making pixel art in a text editor. If your application can't handle it natively, you can convert it with gimp or imagemagick.
For more information see http://en.wikipedia.org/wiki/X_PixMap or my post http://opengameart.org/forumtopic/feature-request-allow-xpm-file-format.
Hope this helps.