>> if you manage to do that I would have no qualms to change to different system
>> or license, but not if that means the user has to read through potentially
>> thousand of source files to find a file that makes his document work
>> differently on his site than on others.
> I'm sure there are lots of ways.  One possibility that springs to mind that
> would not run afoul of the DFSG would be to require the existence of a "flag
> file" in modified distributions of LaTeX.  The LaTeX engine could look for
> this file at some convenience stage in its execution and spew a warning to
> standard output or standard error[2].  I'm not a very sophisticated TeX user,
> but I'm in the habit of reading the warnings it gives me.  I've learned to
> ignore overfull and underfull hboxes, but maybe real TeXperts have such
> self-confidence that they ignore everything.  :)  In any event, it's the
> user's responsibility to read the output the program gives him.
[Note. Instead of sendind this message to the Debian list, I going to send
it to this list only. Reuse the argument if you want.]

If I've understood correctly, this is a complete nonsense. If I get a
document by "John Smith", how can I see if _his_ system has a flag file? I
can only access my own flag file but I'm supposed to know I'm changed my