XPM is a file format whose contents are not hidden, whose
functions are not proprietary and closely held by corporations who would like to manage modes of communication.
Open such a file in a text editor and you can see the
color index--a list of symbols associated with particular colors--and then the pixel data that refers back to this index. It is a model of openness, free of non-disclosure agreements and exclusive authoring tools.
Any of the Icontexts found through this site can be opened as either an html page through a browser, or as an XPM file in an image processing program. Although not all such programs support the XPM format, many do, and three such programs are listed below.