Does the DFSG apply only to computer programs?

No, we apply our standards of freedom to all parts of all software in Debian. This includes computer programs, documentation, images, sounds, etc. The text of licenses themselves in general need not be free, although legal wording itself is often not subject to copyright and hence effectively in the public domain. Although this is a subject of some controversy within the project, in practice sometimes tiny little snippets of non-free text, generally of historic or humorous or intellectual value, are included (eg /usr/share/emacs/21.3/etc/{JOKES,MOTIVATION}). These should not be integral parts of the package, nor included in a non-removable fashion, nor constitute functional parts of the package such as code or documentation. In general we would suggest avoiding such things, but you do not have to go to enormous trouble to find and root them out. In a similar vein, sometimes relevant scientific papers or technical reports of unclear copyright status are included; although they are not ...  more