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
and bidi.
--
Peter Kirk
[EMAIL PROTECTED] (personal)
[EMAIL PROTECTED] (work)
http://www.qaya.org/
