[CEUD-ICT] HTML validation and WCAG 2.0

[Alan M. Dalton]

Hi all,

One of the most interesting [1] issues in WCAG 2.0 is whether or not they
require valid HTML.

WCAG 2.0 can be applied to any technology, so it allows non-HTML content
such as PDF. WCAG 2.0 also allows WAI-ARIA specifically requires some
attributes which cause a validation error for HTML 4.01/XHTML 1.0, but the
benefits of WAI-ARIA outweigh the benefits of that validation error.

When I first looked at WCAG 2.0, I thought they required HTML pages to be
valid. I based that on WCAG 2.0 Principle 4 ("Robust"), which includes
Guideline 4.1 ("Compatible"), which includes Success Criterion 4.1.1
("Parsing"). The current Sufficient Techniques for that Success Criterion
are:
- G134: Validating Web pages
- G192: Fully conforming to specifications
- H74: Ensuring that opening and closing tags are used according to
specification
- H75: Ensuring that Web pages are well-formed
- H88: Using HTML according to spec
To me, that looked like WCAG 2.0 were still pushing for HTML to be valid.

However, there's a very interesting phrase in G134: Validating Web pages:
"Validation does not necessarily check for full conformance with a
specification but it is the best means for automatically checking content
against its specification" [2]. (Thanks to Josh O'Connor for bringing that
to my attention.)

Also, the Sufficient Techniques for Success Criterion 4.1.1 include
ensuring that Web pages can be parsed by using either "H74: Ensuring that
opening and closing tags are used according to specification (HTML)" or
"H75: Ensuring that Web pages are well-formed (HTML)" [3]. It's interesting
[1] that WCAG 2.0 focuses on well-formedness with opening and closing tags
properly nested, instead of requiring that every HTML webpage be valid.

Any thoughts?

[1] That depends on your definition of "interesting"!
[2] http://www.w3.org/TR/2008/NOTE-WCAG20-TECHS-20081211/G134
[3] http://www.w3.org/TR/UNDERSTANDING-WCAG20/ensure-compat-parses.html

Regards,
Alan.
_
Alan Dalton
Accessibility Development Advisor for EtA http://www.nda.ie/eta
Access Officer for NDA http://www.nda.ie

Address: National Disability Authority, 25 Clyde Road, Dublin 4.
E-mail: amdalton at nda.ie
Telephone: 01-6080 406

"Safe Evacuation For All", 23 September 2009: http://tinyurl.com/safeevac
EtA recipients from 2008: http://tinyurl.com/EtA2008
_


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