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[Bug 4961] Erroneous error message when no xmlns attribute on html element in XHTML 1.0

From: <bugzilla@wiggum.w3.org>
Date: Sun, 19 Aug 2007 16:58:31 +0000
To: www-validator-cvs@w3.org
Message-Id: <E1IMo6h-0004Jb-Er@wiggum.w3.org>


           Summary: Erroneous error message when no xmlns attribute on html
                    element in XHTML 1.0
           Product: Validator
           Version: 0.8.1
          Platform: All
               URL: http://validator.w3.org/check?uri=http%3A%2F%2Fiamback.c
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: check
        AssignedTo: dave.null@w3.org
        ReportedBy: iamback4now@yahoo.com
         QAContact: www-validator-cvs@w3.org
                CC: iamback4now@yahoo.com

When a document declared as DOCTYPE XHTML 1.0 (strict) does not declare an
xmlns attribute on the html element, the validator currently (not before 0.8
apparently) gives an error message like this :

Line 2, Column 1: Missing xmlns attribute for element html. The value should
be: http://www.w3.org/1999/xhtml.

<html xml:lang="en">

Many Document Types based on XML need a mandatory xmlns="" on the root element.
For example, the root element for XHTML will look like:
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">

This appears to be a bug, for the following reason:

The DTD for XHTML 1.0 strict
(http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd) contains this definition: 

<!ATTLIST html
  xmlns       %URI;          #FIXED 'http://www.w3.org/1999/xhtml'
Note that is says FIXED, not REQUIRED. While it may well be true that "Many
Document Types based on XML need a mandatory xmlns="" on the root element." as
stated with the error message, that is not the case with XHTML 1.0 strict (or
transitional or frameset), all of which declare a FIXED value of

FIXED means it can have only the defined value, and that value is /already/
fixed; thus is it does not need to be declared (as it would if it were defined
as REQUIRED); and if it /is/ declared (allowed), then it cannot have any other
(see also my comment #10 on issue 68

I am basing this interpretation of FIXED (vs. REQUIRED) on several discussions
with W3C people, notably a lengthy discussion with Al Gilman during an FPWG
meeting in Amsterdam (in May 2001) on XML accessibility where I (as then member
of the ATAG) was invited to be present. On the strength mainly of this
discussion, and in my role (then) as Product Manager for Allaire HomeSite, I
even deliberately created the "Tag Editor" for the html element in such a way
that while it /displays/ the xmlns value while editing, it does *not* add this
as an attribute to the html tag written out by the tag editor.

I find it therefore quite curious, and disappointing, that suddenly (since v.
0.8) now the validator will state that documents that do not declare the FIXED
xmlns value as an attribute are in error.

It is of course possible that several W3C people's interpretation of FIXED vs.
REQUIRED were in error. If this is the case, please refer to a document that
clearly states that an attribute defined as having a FIXED value in a DTD
*must* be declared in a document that conforms to that DTD. In other words, a
document /preceding/ the XHTML 1.0 DTDs, defining the exact meaning of FIXED
vs. REQUIRED. (In yet other words: what, exactly, causes the developers of the
validator to think that FIXED means 'mandatory'?)

Until I see such a document (I have never been able to track down anything), I
will continue to believe that all XHTML 1.0 documents that do not declare an
xmlns attribute on the html (root) element (which will include nearly all XHTML
documents created with HomeSite 4.5 and 5.x) are, in fact, quite valid, and the
error message issued by the validator is a bug.
Received on Sunday, 19 August 2007 16:58:34 UTC

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