Re: [CSS21] out of range unicode escapes

This is cross posted to the public internationalisation core.

On the I18N core, we have had some discussion on this topic, an this is
the result of our discussion:

In http://lists.w3.org/Archives/Public/www-style/2007Apr/0045.html the
CSS WG propose replacing all out of range Unicode escapes with
the "replacement character" (U+FFFD).

This behaviour is not appropriate because U+FFFD is specified as a
Replacement Character to be "used as a substitute for an uninterpretable
character *from another encoding*".
see: http://unicode.org/glossary/#replacement_character .

The correct response to any invalid Unicode escape should be to treat it
as a parse error (see section 4.1.8), in the same way that any other
invalid or unexpected character would be.

For clarity Add this text to 4.1.3 at CSS 2.1
http://www.w3.org/TR/CSS21/syndata.html#q6  :

    If the number is outside the range allowed by Unicode (e.g.,
    "\110000" is above the maximum 10FFFF allowed in current Unicode),
    then the parser should treat this as parse error and A user agent
    must ignore a declaration containing this invalid property name or
value.

see: http://www.w3.org/TR/CSS21/syndata.html#ignore

----
David Clarke