Re: Validating for Accessibility

I propose that this discussion move to the ER mailing list entirely, unless
anyone objects. So please make that the recipient of further posts if nobody

To the substance:

This is an interesting approach. It seems much like the approach taken in
developing the schematron accessiblity validation. (for a list of tools
including schematron, Bobby and others, see the ER tools list.) The question is,
of course, what can be tested using SGML/XML validity type checking?

I cannot speak fgor the range of developers out there, but as these things
are being built into authoring tools (like Dreamweaver, IBM's WebSphere
products, etc) I assume there is interest in a variety of methods for
checking, at the very least to explore what benefits they can offer, and
potentially of course there is a useful tool to be developed.

In fact I think that better heuristics to generate warnings, and simpler
approaches to the test which are relatively simple, are both going to be part
of the solution for a good accessibility testing (and repairing) aid.

As a final note, your opinion on whether it would be easy and / or useful to
generate a machine-readable output format (the EDL / EARL project that the ER
group is working on) would be interesting.


Charles mcCN

On Wed, 27 Dec 2000, Nick Kew wrote:

  [ I may post this to more than one place; apologies for any duplication ]

  I have for some time been contemplating a slightly mad idea of using
  formal validation for accessibility checks.  The goal of the exercise
  is an alternative to "bobby", based on a validating SGML engine.

  Obviously this kind of accessibility checking is limited by what can
  be expressed in SGML (or XML) terms.  This may be rather less than
  "bobby" can do, but on the other hand it is also less likely to mess up
  and generate bogus advice based on heuristic parsing.  I have given it
  some thought, and I envisage a series of DTDs designed for accessibility,
  and hacked using SP's architectural forms to allow different checks to be
  INCLUDEd or IGNOREd.  Modular XHTML may offer another approach, but I have
  yet to get to grips with how it will work.

  As a first demonstrator for the principle, I have added an "Accessibility
  Mode" to the validator at <URL:>.
  This rather crude prototype works by validating against an
  accessibility-enhanced variant on W3C's HTML 4.  This is a quick hack:
  among other things I would propose to build a properly engineered
  system on Code Valet (direct WWW interface to SP) rather than Page Valet
  (Perl CGI).

  Rather than continue forever in isolation, can I ask for comments on
  this proposed project?
    * Is it worthwhile?
    * Is there interest in the project - anyone?
    * Is it appropriate to use these lists as a discussion forum for it?

Charles McCathieNevile    phone: +61 (0) 409 134 136
W3C Web Accessibility Initiative            
Location: I-cubed, 110 Victoria Street, Carlton VIC 3053, Australia
until 6 January 2001 at:
W3C INRIA, 2004 Route des Lucioles, BP 93, 06902 Sophia Antipolis Cedex, France

Received on Wednesday, 27 December 2000 19:11:43 UTC