Maybe instead of sinking further and further into little details of how files are verified to be standard LaTeX and the distinction between the LaTeX engine and the files it reads and all that good stuff, we could back up a step? This all really an attempt to procedurally implement an underlying concern. Maybe the concern itself could be directly expressed in the license, abstracted away from its implementation?
Something like this: You must not cause files to misrepresent themselves as approved by the official LaTeX maintenance group, or to misrepresent themselves as perfectly compatible with such files (according to compatibility criteria established by the official LaTeX maintenance group). Would this satisfy the LaTeX people? Because I think it would satisfy the DFSG. It might (arguably, perhaps) even be GPL compatible, if the authorship representation parts of the GPL are properly construed. -- Barak A. Pearlmutter <[EMAIL PROTECTED]> Hamilton Institute, NUI Maynooth, Co. Kildare, Ireland http://www-bcl.cs.unm.edu/