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From: ok@cs.mu.oz.au (Richard O'Keefe)
Newsgroups: comp.lang.prolog
Subject: Re: Non-ASCII characters, suggestion and question
Message-ID: <2432@munnari.oz.au>
Date: 15 Oct 89 10:31:55 GMT
References: <2422@munnari.oz.au> <ALBERTO.89Oct14145937@tove.umd.edu>
Sender: news@cs.mu.oz.au
Lines: 63

I wrote:
:  The question is whether diactrical marks should precede or follow the
:  letter they modify.  I prefer \:e' because I read it as "e-acute" and so
:  expect the diactrical mark second.  But I believe there is a French
:  convention that involves writing the diactrical mark first.

In article <ALBERTO.89Oct14145937@tove.umd.edu>,
alberto@tove.umd.edu (Jose Alberto Fernandez R) wrote:
: Well, historically on typewriters the marks are typed first and then
: the character this is for mechanical reasons (the mark does not move
: the page and the paper moves when the marked letter is typed).

I still have a typewriter with non-advancing keys.

: On the other hand, TeX and LaTeX have defined a code for these marks
: and at least for the folks that use [La]TeX it will be nice if you only
: need to learn one convention.

For the benefit of those without [La]TeX, here is the LaTex scheme:

	Code	Meaning			Present use in Prolog
	\`x	grave accent		(available)
	\'x	acute accent		a quote (') followed by x
	\^x	circumflex		control-X
	\"x	umlaut/diaeresis	a quote (") followed by x
	\~x	tilde			(available)
	\=x	macron (overbar)	(available)
	\.x	dot			(available)
	\ux	breve			(reserved)
	\vx	"v" accent		(reserved)
	\Hx	two acutes		(reserved)
	\txy	"tie" over x and y	tab followed by x and y
	\cx	cedilla			continuation followed by x
	\dx	dot underneath		DEL followed by x
	\bx	underbar		backspace followed by x
	\oe	oe ligature		(reserved)
	\ae	ae ligature ("ash")	BEL followed by e
	\aa	a ring			BEL followed by e
	\o	slashed o		(reserved)
	\l	slashed l		(reserved)
	\ss	ess-tset		space followed by s	
	\pounds	pound sterling sign	(reserved)
	\copyright  copyright sign	continuation followed by opyright
	\S	section sign		space
	\P	pilcrow			(reserved)
	?`	upside-down ?		? followed by `
	!`	upside-down !		! followed by `

We cannot use this scheme, because too many of the sequences are already
in use.  The ?` and !` ligatures in TeX would be particularly painful to
add to Prolog.  TeX permits the construction of accented characters which
have no counterpart in ISO 8859/1, the MS-DOS character set, or the Mac
character set.  That's fine, no problem.  The thing which *really* makes
it unacceptable is that it has no way of expressing some of the
characters which ARE in the ISO 8859/1 character set, such as eth and
thorn, guillemots, Yen sign, ...

On the other hand, with the example of mechanical typewriters, [La]TeX,
and a French scheme I've seen, it does appear that putting the accents
first would be more consistent with "existing practice".  Too bad.

Using \:'e for e-acute would not be so much unlike \'e that a TeXnician
would be confused, I hope.