I noticed in this LaTeX configuration document a reference to something called "fsfTeX." Quote:
Since we have been prompted, despite our misgivings, to document how to do this by members of the League for Programming Freedom, it seems appropriate to describe here a possible modification of LaTeX to produce a system called fsfTeX.
The document goes on to talk about modifying the "LaTeX kernel." I haven't found much information about what fsfTeX was except an old Debian mailing list post talking about licensing.
What was fsfTeX and what sorts of modifications did it involve, and why?