What is e-TeX?
While Knuth has declared that TeX will never
change in any substantial way, there remain
things that one might wish had been done differently, or indeed
implemented at all.
The NTS project set out to produce an advanced replacement for
TeX, to provide a basis for developing such modifications: this
“New Typesetting System” would share Knuth’s aims, but would
implement the work in a modern way taking account of the lessons
learned with TeX. While a first demonstrator NTS did
appear, it wasn’t practically useful, and the project seems no longer
In parallel with its work on NTS itself, the project developed
a set of extensions that can be used with a (“true”) TeX system.
Such a modified system is known as an e-TeX system, and the concept
has proved widely successful. Indeed, current TeX distributions
are delivered with most formats built with an e-TeX-based system (for
those who don’t want them, e-TeX’s extensions can be disabled, leaving
a functionally standard TeX system).
The extensions range from the seemingly simple (increasing the number
of available registers from 256 to 32768) through to extremely subtle
ConTeXt has required e-TeX for its operation
for some time, though development is now focused on the use of
Some LaTeX packages already specify the use of e-TeX. Some such
packages may not work at all on a non-e-TeX system; others will
work, but not as well as on an e-TeX system. The
LaTeX team has announced that future LaTeX
packages (specifically those from the team, as opposed to those
individually contributed) may require e-TeX for optimum performance.
- systems/e-tex (or browse the directory); catalogue entry
This answer last edited: 2011-07-13
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