From: mackay@cs.washington.edu (Pierre MacKay)
Newsgroups: comp.text.tex
Subject: Inputting accented characters (postpositive accents)
Date: Thu, 21 Jan 93 09:17:14 -0800
Organization: Info-Tex<==>Comp.Text.Tex Gateway
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In principal, this is an excellent idea, and I have pushed for it since
way back in the late 60s, but it is not without its difficulties.

Knuth's accent primitive was never intended for large amounts of
running text, as he makes clear in several places where he
comments on it.  It was to provide the necessary low-level
solution to the immediate problem (fairly acute for a mathematician)
of citations from European literature.  He never contemplated
keyboarding {\it Les Miserables} with the accent primitive.

When you propose a postpositive convention, however, you have to make a
distinction between keystrokes and input coding.  The editor you or
your clients use may very well manage the handling of keystrokes in
the way you intend but when you send those keystrokes to a program as
codes, you may get unexpected results.  How do you distinguish
``Souse'' (in quotes) from ``Souse'', with (sic) "accent grave
over the E" (W. C. Fields, in {\it The Bank Dick}).  The easy answer
(too easy) is to say that the French use << >> and not `` '', but
the French are not the only users of e-acute.  UNICODE has moved in the
direction of postpositive accent conventions, and when all or most of us have
16-bit character software I think the decision will be seen as very much
the correct one,  but we have to live with 8-bit.

About the only way to isolate a sufficient number of accents so they can
be used in a low-level "glass tty" environment as well as on special
and usually proprietary systems, is to provide an intermediate code.
I use the +, because the mathematical symbol, when needed, can and should
always be set in math mode ($+$).  But no one wants to type e+' for every
occurrence of e-acute, nor should they.  The trigraph convention is there
as a backup, in case you have to edit a text from a plain ascii terminal
running nothing but communications software (as I am right now).  The editor
program used by a multilingual author ought to provide a lot of preaccented
glyphs tied to unique eight-bit (ultimately 16-bit) codes, and the translation
to trigraphs ought to be invisible to the user 99 44/100% of the time.
We do that with both Greek and Turkish.  The PC-Write Turkish editor produces
many codes in the 0x80-0xFF range, and those are invisibly translated
by the TeX macro file to digraphs and trigraphs in a post-positive
accent convention.  The digraph convention is there so that files can
be sent through the mail, and so that last minute editing can be done
on displays that know nothing of the PC-Write Turkish convention.

Of course, there have to be fonts with ligature tables that interpret
digraphs and trigraphs and produce accented TeX characters.  That assumes
the existence of a font with composite accented characters, such as
the DC (Cork) encoded fonts being developed at the present time.

If you have an editor whose display codes exactly match the DC encoding,
and a set of display fonts that will produce the correct glyphs,
there is nothing left to do but make sure that your clients are
comfortable with the keystroke sequence.  Otherwise they can
use some piped interpretation such as

MS Word | translator | TeX.

The important point is that the choice of keystroke sequence for the
comfort of the author is not really TeX's business.  It is the business
of an editor or a "Word Processor".  Once an unambiguous coding has been
established within the editor, it is relatively easy to interpret that coding
in a way that TeX will handle effectively, but the author usually does
not need to worry about the specifics of the interpretation.


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