From: Philippe Verdy (email@example.com)
Date: Wed Aug 13 2003 - 17:07:40 EDT
From: "Peter Kirk" <firstname.lastname@example.org>
> On 13/08/2003 11:09, Philippe Verdy wrote:
> >... For this reason, defective
> >combining sequences (combining characters without a leading base
> >character) should be forbidden (invalid for XML).
> If there is even the remotest possibility of this happening, we need
> know quickly! Defective combining sequences are legal Unicode and are
> now being suggested for use in Hebrew e.g. for holam male. But such a
> definition would be useless if XML restricts the texts it can
> to a subset of Unicode excluding such sequences.
I did not notice that the discussion about Hebrew holam male was
In fact I don't know anything about the hebrew alphabet so I could not
understand the semantics discussed, and so di not note that <holam, vav>
was a "defective" encoding (in terms of combining sequences).
When using the term "forbidden", it was only related to possible
problems with XML, but the term was certainly too much expeditive.
However, given that possible security and parsing issues do exist, the
case of <holam, vav> used to encode "holam-male" may be another
argument to propose a neutral/invisible base character for combining
characters. For the case of Hebrew, it then needs to have a "letter"
behavior, but for the case of other isolated diacritics in Latin,Greek
Cyrillic, and probably also Hiragana, Katakana (voice marks) it should
better be handled as a symbol.
I suggested several semantics for this invisible character(s) in a
- A invisible symbol
- An invisible LTR letter
- An invisible RTL letter
all of them having a *compatibility* decomposition (or NFKD form) as
a SPACE like other existing spacing combining marks, but not being
canonical equivalent of SPACE (to keep separately the legacy semantics,
properties, behavior and known caveats unchanged and
implementation/usage-dependant, as they are now with SPACE+NSM
which could then be discouraged in Unicode and strongly deprecated
This archive was generated by hypermail 2.1.5 : Wed Aug 13 2003 - 18:06:27 EDT