NNBSP (was: A last missing link for interoperable representation)

[Richard Wordingham via Unicode]

On Tue, 15 Jan 2019 13:25:06 +0100
Philippe Verdy via Unicode <unicode at unicode.org> wrote:

> If your fonts behave incorrectly on your system because it does not
> map any glyph for NNBSP, don't blame the font or Unicode about this
> problem, blame the renderer (or the application or OS using it, may
> be they are very outdated and were not aware of these features, theyt
> are probably based on old versions of Unicode when NNBSP was still
> not present even if it was requested since very long at least for
> French and even English, before even Unicode, and long before
> Mongolian was then encoded, only in Unicode and not in any known
> supported legacy charset: Mongolian was specified by borrowing the
> same NNBSP already designed for Latin, because the Mongolian space
> had no known specific behavior: the encoded whitespaces in Unicode
> are compeltely script-neutral, they are generic, and are even
> BiDi-neutral, they are all usable with any script).

The concept of this codepoint started for Mongolian, but was generalised
before the character was approved.

Now, I understand that all claims about character properties that cannot
be captured in the UCD should be dismissed as baseless, but if we
believed the text of TUS we would find that NNBSP has some interesting
properties with application only to Mongolian:

1) It has a shaping effect on following character.
2) It has zero width at the start of a line.
3) When the line-breaking algorithm does not provide enough
line-breaking opportunities, it changes its line-breaking property
from GL to BB.

Or is property (3) appropriate for French?

Richard.