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Date:         Wed, 10 Feb 2010 23:12:34 +0100
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From: Philipp Stephani <st_philipp@YAHOO.DE>
Subject: Re: LaTeX3 8-bit only?
To: LATEX-L@listserv.uni-heidelberg.de
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Status: R

Am 10.02.2010 um 21:27 schrieb William F Hammond:

> Joseph Wright <joseph.wright@MORNINGSTAR2.CO.UK> writes:
> 
>> . . .
>> I was thinking of input encodings, where my point was (supposed to) be
>> that something like the inputenc "utf8" approach would be an approach
>> I hope we can avoid as there are better solutions (in the form of
>> engines which deal with the issue). (Of course, that leaves UTF-16
>> issues, but I'd hope that engine developments can help out).
>> 
>> (I'd point out that LaTeX3 code is intended for use in new documents,
>> and the rest of the computer world is standardising on UTF-8 as far as
>> I can see. So I'd hope very much that having an approach based on this
>> concept is not too risky.)
> 
> At some point I expect that LaTeX will want to provide for arbitrary
> unicode "word" characters in command names.

That is already possible with XeTeX:

\documentclass{minimal}

\begin{document}

\def\äηあש{Hello world}

\ttfamily\meaning\äηあש

\end{document}

It would also be possible with pdfTeX and UTF-8 if the code units 0x80 to 0xFF were not active. Perhaps pdfTeX could be patched so that code units in this range could be active and be part of control sequences at the same time. On the other hand one could leave them as letters and use the ligature mechanism and virtual fonts, similar to how current fonts handle non-BMP characters. However, any of these has to be done quickly: If LaTeX 3 won't be finished before LuaTeX, it will be obsolete anyway.