Re: Subsettability of the SVG document

I think in general it's going to be futile to have the browser check that
SVG fonts adhere to a sublanguage of SVG+CSS that make subsetting
tractable. The languages are just too powerful. It's also counterproductive
since that would limit the ways people can use SVG Fonts even if they don't
care about subsetting. New SVG features might break subsettability so we'd
have a lag between a feature being added to SVG and being whitelisted for
SVG fonts.

I think people should build subsetting tools that can handle particular
sublanguages of SVG+CSS and report errors when they encounter stuff they
can't handle. Then it's up to font authors to restrict themselves if they
want their fonts to be subsettable. The community can work out its own best
practices for this.

Another thing is that to reduce memory usage we will probably eventually
need a way to separate glyphs into multiple independent documents within a
font. Of course that would enable some easy subsetting by throwing out
documents that don't contain any glyphs you need.

Rob
-- 
"If we claim to be without sin, we deceive ourselves and the truth is not
in us. If we confess our sins, he is faithful and just and will forgive us
our sins and purify us from all unrighteousness. If we claim we have not
sinned, we make him out to be a liar and his word is not in us." [1 John
1:8-10]