[Bug 12839] @id: Define how Unicode normalization affects the 'unique identifier' status

http://www.w3.org/Bugs/Public/show_bug.cgi?id=12839

--- Comment #3 from Leif Halvard Silli <xn--mlform-iua@xn--mlform-iua.no> 2011-06-01 11:28:52 UTC ---
(In reply to comment #2)
> I request resolving this by comparing identifiers code-point-for-code-point
> without normalization before comparison. 

I recommend to file a separate bug in order to get HTML5 to spec how to resolve
IRIs that either contain NFD normalized characters or point to identifiers with
 NFD normalized characters therein.

This bug is only about the meaning of "unique identifier" whenever two idrefs
differ only with regard to their normalization. UA behaviour is of course
relevant to consider when resolving this bug. But so is also the confusion that
authors and users would experience if two @id-s with the same characters
inside, are considered unique because they use different normalization.

> (In reply to comment #0)

> > that <a href="#a&#x30a;">link</a> targets <p id="&#xe5;">
> > whereas <a href="#&#xe5;">link</a> targets <p id="&#xe5;">
> 
> Are you sure you meant exactly what you wrote? You next paragraph suggests that
> you didn't?

I already corrected myself. See comment #1. 

> > Thus, today's user agents do actually treat them as unique identifiers, despite
> > that they both refer to the same "å" (&#xe5;).  
> > 
> > However, in order toi avoid author confusion as well as user confusion, this
> > should not be considered valid.
> 
> Until very recently, Validator.nu treated failure to be in NFC as an error. Now
> it treats it as a warning, because there was no normative trail from HTML5 to
> charmod-norm C300.

Not deployed yet? Validating this code:

<p id="a&#x30a;"><p id="&#xe5;">

I still get this error message:

]] Error: The value of attribute id on element p from namespace
http://www.w3.org/1999/xhtml is not in Unicode Normalization Form C. From line
1, column 1; to line 1, column 17: <p id="a&#x30a;"> [[

It is good if this becomes a warning rather than an error. *However*, for @id,
then validator should also report uniqueness *errors*.

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Received on Wednesday, 1 June 2011 11:28:55 UTC