Re: Printing and Displaying Dependent Vowels

From: Peter Kirk (
Date: Mon Mar 29 2004 - 11:33:34 EST

  • Next message: Peter Constable: "RE: Printing and Displaying Dependent Vowels"

    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 (personal) (work)

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