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[css3-values] Issue 18 proposal - defining an always-invalid URL

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Thu, 28 Jun 2012 12:08:10 -0700
Message-ID: <CAAWBYDCDXzm=EC+4O7eqOPJrZFJozba3-xccfUR91JZr+EQOiA@mail.gmail.com>
To: www-style list <www-style@w3.org>
Issue 18 on CSS3 Values hasn't been resolved yet:
http://dev.w3.org/csswg/css3-values/issues-lc-2012.html#issue-18

To summarize, attr() needs to return a "default value" for each type,
for when the attribute can't be parsed as the type or when it's
missing.  For URLs, we'd like the default value to be always-invalid,
or never-resolvable, so that it fails no matter what context you're
using it in.  (It can't, for example, resolve to some UA-defined HTML
404 page, as that might be interpretable by some future CSS property
that, say, de-magic-ifies iframes.)  However, there is no such URL in
existence so far.

We propose just defining it to be the url "about:invalid", and then
subsequently getting that URL added to the about: registry.

Any objections?

~TJ
Received on Thursday, 28 June 2012 19:09:00 GMT

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