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Re: Revised LaTeX Project Public License (LPPL)

> Is this really saying that I can distribute The Work, or ANY Derived Work,
> under any license I choose, as long as 7a (which is really just a pointer
> to 5a, which says that if you're not the current maintainer, you must make
> modifications sufficiently obvious) is satisfied?
> For example, you could distribute The Work under a DWTFYW[0] license, plus
> the condition that it never be distributed as files named pig.*

LPPL has been through various versions, but the above is essentially a
description of all of them. The wording changes between versions have
been clarifications and additional explanations an responses to
objections from various quarters, but essentially the above does
describe the main intention of the latex licence.

> I'm curious what the reasoning is for this clause.

I'll try to avoid the F word in the following discussion has it has a
specific meaning here...

LaTeX  source code is completely available (which in fact is a necessary
feature of the way latex works, but even if it wasn't,  making code
available would be a good thing). We want to encourage people to take
those sources and modify and adapt things to make improvements or just
uses that were not previously envisioned.  However in addition to its
role as a typesetting language, a major use of latex is as a document
interchange format and these documents are often written by people who
are not the people inclined to make code changes or with the skills to
revert code changes if they find themselves using a modified version.
For this purpose it is important to have a reference version that may be
relied upon to process documents in compatible, and preferably
identical, ways at different sites.


The whole point of the latex licence is to allow some people to make
completely arbitrary code changes, while at the same time allowing
anyone to know whether or not they are using a standard setup that may
be reliably used as a basis for compatible or archival documents.

The simple idea at the start was "if you change it, change the name"
which is basically an idea copied from the comments in Knuth's files for
tex and metafont and the sources for computer modern fonts.  For several
reasons (not entirely unreasonable and debated at length on this list)
filename restrictions are problematic, so this version of LPPL floats
alternatives relating to the user-oriented messages that typically come
on the terminal when you run latex. This means the licence gets more
complicated as you have to word it so it means something in a world
where latex runs on systems with no real terminal output, and the actual
command that is used to invoke "latex" is not within the control of the
latex distribution: latex is just a set of macro definitions, the
executing program is something else, although typically it ends up being
called latex at the user level. However if this complication makes 
it legally acceptable to Debian (and similar distributions) and still
maintains the basic reasons for having an LPPL at all, then the effort
will have been worth it, I hope.


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