Comments on CSS3 Fonts module

I believe that the fonts module must specify a suggested behavior when faced with a document that specifies a character it can not render because no glyph is available. Current browsers sometimes display a question mark, sometimes an empty square box, and sometimes display the Unicode "? inside a diamond" replacement character. A plain question mark is not a clear enough indication that the character is missing, and can lead to significant confusion in some cases, especially when combining glyphs are used. This glyph is somewhat jarring in its appearance, but this is the only sure way to make it clear to the reader (and author) that something is amiss, as both the empty square box and question mark are valid characters in their own right, and can legally appear in a HTML document.

Also, the set of characters specified in the current HTML DTDs is not really sufficient to display many important characters, including typographical marks, combining diacriticals, and many technical symbols. This module should either mandate, or at least encourage, that user agents support a larger range of characters, to support higher quality typography as well as technical documents. Or perhaps a property could be added that would allow the author to specify the rendering behavior, and to specify an image to use as the replacement character.

I also believe that the possible values for font-style should more closely match those available for fonts--which often have variations such as "heavy" in addition to "itallic", where all are related to the same font, and often presented to the user as such, instead as separate fonts with similar names.