Re: [css3-values] attr() function

> 
> 
> If introduced as global value the attr() function should apply to every property
> and to every language that has notion of attributes, in my opinion. Note that
> theoretically HTML UAs might reject <p color="red"> because it is not valid,
> but if they do not it should be supported as expected.

There is ambiguity as to whether the value is a string or a lexical 
value.  In the latter case, as in this example, it requires lexical
scanning at a late stage.

> <color> might be a problem though as colors are often specified as '000000'
> which is not valid and should be rejected per CSS 2.1. It might be a good thing

I'm not sure why such bad practices should be encouraged.  If the colour
is being mis-specified, the author is unlikely to be providing a valid
style sheet.  Even if the correct syntax is used, it only encourages
presentational HTML.