are meant to represent the capital Greek letters tau, epsilon, and chi, as TeX is an abbreviation of τέχνη ( ), Greek for both "art" and "craft", which is also the root word of technical. English speakers often pronounce it , like the first syllable of technical. Knuth instructs that it be typeset with the "E" below the baseline and reduced spacing between the letters. This is done, as Knuth mentions in his TeXbook, to distinguish TeX from other system names such as TEX, the Text EXecutive processor (developed by Honeywell Information Systems). Fans like to proliferate names from the word "TeX"—such as TeXnician (user of TeX software), TeXhacker (TeX programmer), TeXmaster (competent TeX programmer), TeXhax, and TeXnique. Community Notable entities in the TeX community include the TeX Users Group (TUG), which publishes TUGboat and The PracTeX Journal, covering a wide range of topics in digital typography relevant to TeX. The Deutschsprachige Anwendervereinigung TeX (DANTE) is a large user group in Germany. The TeX Users Group was founded in 1980 for educational and scientific purposes, provides an organization for those who have an interest in typography and font design, and are users of the TeX typesetting system invented by Knuth. The TeX Users Group represents the interests of TeX users worldwide. The TeX Users Group publishes the journal TUGboat three times per year; DANTE publishes four times per year. Other user groups include DK-TUG in Denmark, in France, GuIT in Italy, NTG in the Netherlands and UK-TUG in the United Kingdom; the user groups jointly maintain a complete list. Extensions List of TeX extensions See also Comparison of document markup languages Formula editor List of document markup languages MathJax - TeX on Web pages via JavaScript MathTime New Typesetting System – a TeX reimplementation (discontinued) PGF/TikZ PSTricks xdvi – a program for viewing .dvi files Notes References Sources . . The source code of the book in TeX (and a needed set of macros ) is available online on CTAN. It is provided only as an example and its use to prepare a book like The TeXbook is not allowed. . The full source code of TeX; also available on CTAN. Being written using literate programming, it contains plenty of human-readable documentation. . . Reprinted as . contains extensive documentation about the algorithms used in TeX. . . . on AMS-TeX. . External links TeX Users' Group . Eijkhout, Victor.