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Re: DFSG2: The patch exception

Wichert Akkerman <wakkerma@cs.leidenuniv.nl> said:

> TeX does not really prohibit patches, it only does not allow that a
> patched version is redistributed under the name TeX.

The introductory remarks in the file `tex.web' (Donald Knuth's
implementation of TeX in a language called WEB which mixes Pascal with
verbose comments in TeX) say that that particular file is not to be
changed by people other than DEK, and that modifications must be
distributed as patches (`change files' in WEB jargon).

This requirement is independent of the requirement that programs may
only be called TeX if they pass the Trip test (TeX's automatic test
suite). There have been several re-implementations of TeX in non-WEB
languages that were done from scratch with reference to the algorithms
described in `TeX: The Program' (a book by Donald Knuth which
essentially contains `tex.web' run through the Weave pretty-printer).
The resulting programs pass the Trip test, and they may be (and have
been) distributed as `TeX' even though they don't include code from the
original tex.web at all.

Anselm Lingnau ......................... lingnau@tm.informatik.uni-frankfurt.de
As an adolescent I aspired to lasting fame, I craved factual certainty, and I
thirsted for a meaningful vision of human life - so I became a scientist. This
is like becoming an archbishop so you can meet girls.            -- M. Cartmill

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