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Re: fixed-length escapes

From: C. M. Sperberg-McQueen <cmsmcq@acm.org>
Date: Sat, 13 Jul 2002 14:43:18 -0600
Message-Id: <5.1.0.14.1.20020713143603.028c3698@localhost>
To: Martin Duerst <duerst@w3.org>
Cc: www-i18n-comments@w3.org, w3c-i18n-ig@w3.org

At 2002-07-12 01:22, Martin Duerst wrote:
>Hello Michael,
>
>Many tanks for your comment.
>
>ISO 2022 works on a different level than the escape sequences
>we are talking about.

Yes, I know.  I was just wondering:  if we wish (as in the
character model spec) to partition the set of imaginable
escape sequences into those which are OK and those which
should not be used, it seems interesting to consider the
class of escape sequences which (a) operate on the level
the character model spec is attempting to constrain, and
(b) have the same abstract structure / grammar as those
defined in ISO 2022, namely

   esc-seq ::= esc-init esc-medial* esc-final

where esc-medial and esc-final (and, I guess, conceivably
also esc-init) are character classes.

>While it is in theory possible to define
>escape sequences of the type you describe below on the level
>of a document format or something similar, I haven't really seen
>such a case at all.

I don't think I have either, at the application level.
(Although I wonder whether some parts of the TeX syntax
would count.  Perhaps not.)

>An example would be:
>
>&#y2345%    would be U+2345
>&#y2345$    would be U+12345
>&#y2345(    would be U+22345
>...
>&#y2345!    would be U+D2345
>...
>
>The more I think about it, the more I guess it's weird
>enough that we don't have to care about it.

You may be right.  I think my leaning would be to make explicit
that these do fall into the category of deprecated escape-sequence
designs.

Michael
Received on Saturday, 13 July 2002 16:55:10 GMT

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