Re: [css-fonts-3] i18n-ISSUE-296: Usable characters in unicode-range

Richard Ishida wrote:

> 4.5. Character range: the unicode-range descriptor
> http://www.w3.org/TR/2013/WD-css-fonts-3-20130711/#unicode-range-desc
> 
> "Valid Unicode codepoint values vary between 0 and 10FFFF
> inclusive." Do we need to say something about characters that cannot
> be used, such as surrogate codepoints?
> 
> Perhaps what is meant is that the codepoint values cannot be higher
> than 10FFFF or lower than 0. In this case, perhaps the spec should
> say that the codepoint space (range) is between 0 and 10FFFF, rather
> than give the impression that all values in that space are
> acceptable.

Hmm, unicode ranges are used to indicate *possible* coverage ranges
for fonts. The actual range used in font matching is ultimately
determined by the intersection of the unicode-range descriptor value
with the actual character map of the font.  There's no attempt to
separate actual "valid" Unicode values from ones that are invalid.  I
don't think I see a need here to discuss the nitty gritty of surrogate
handling.

Cheers,

John Daggett