From: Doug Ewell (dewell@adelphia.net)
Date: Fri Nov 26 2004 - 17:24:30 CST
Peter Kirk <peterkirk at qaya dot org> wrote:
> So I only raised this issue to clarify exactly how NBSP should be used
> in such cases. Although I have been rather confused by the responses I
> have received, I think the situation is clear as follows: NBSP may be
> used with a combining mark at the start of a word, but should be
> preceded by ZWSP to ensure a break opportunity before the word
> (although this should become unnecessary if the proposed revision to
> UTR #14 is accepted) and also by RLM to ensure correct bidi behaviour.
>
> Please let me know if any of you disagree with this conclusion.
The part about NBSP per se seems correct: it is to be used as the base
for a combining mark wherever INVISIBLE LETTER would have been used.
Most "break opportunities" are between words, a concept often indicated
by an ordinary space (U+0020). So you wouldn't generally have to
precede *every* combination of NBSP+combining mark with ZWSP "to ensure
a break opportunity," only those combinations preceded by a character
other than U+0020 that might inhibit the break. For example, if you
wanted to ensure a break opportunity following U+2014 EM DASH, you would
probably use the ZWSP, but you don't have to use it everywhere.
I also wonder whether the RLM is needed for a construction that is
expected to occur amid a sea of Hebrew. U+00A0 is of type CS, which is
weak directional, meaning its directionality is dictated by that of
surrounding characters. If the surrounding characters are Hebrew (RTL),
the RLM seems redundant (though of course not "forbidden").
-Doug Ewell
Fullerton, California
http://users.adelphia.net/~dewell/
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