From: Peter Kirk (email@example.com)
Date: Mon Mar 29 2004 - 11:33:34 EST
On 29/03/2004 06:56, John Cowan wrote:
>Peter Kirk scripsit:
>>Using NBSP rather than SPACE has several advantages, and has long been
>>specified in Unicode, although not widely implemented. It is less likely
>>to occur accidentally. But it has disadvantages, especially that it will
>>always be a spacing character, whereas for display of isolated Indic
>>vowels no extra spacing is required.
>You don't actually say so, but you give me the impression that you think
>NBSP is a fixed-width space. It isn't; it can assume any width greater
>than zero, just as SPACE can; in particular, when used before a NSM, I
>would expect it to have the same width as the NSM.
Well, as I understand it NBSP is often expected to be a fixed-width
space, and it is in many implementations. In fact I think it ought to
be, whether or not this is actually specified. But there ought to be a
character which is explicitly NOT fixed width to carry NSMs. Also you do
say that NBSP must have a width greater than zero, but for some
combining marks (those which are not non-spacing, and arguably even some
which are) this base character should have zero width.
>>I would like to repeat my earlier proposal for a new character ISOLATED
>>COMBINING MARK BASE. This character would have no glyph, and the general
>>properties of a letter. Its spacing would be just as much as required
>>for proper display of the combining mark - which would be zero for
>>combining marks which have their own width.
>Except for not being letters, SP and NBSP have, or ought to have,
>exactly this behavior.
Well, there are several differences. An obvious one is that a line break
is permitted after SP (but before the combining mark?) And they are
different for a number of algorithms including those for text boundaries
-- Peter Kirk firstname.lastname@example.org (personal) email@example.com (work) http://www.qaya.org/
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