[Irl-dean] Accessibility of CHM Format

[Barry McMullin]

On Wed, 8 Jun 2005 drice at nda.ie wrote:

> There are some fundamental accessibility issues here that, dare
> I say it, circumvent the NDA IT Accessibility guideliens for
> the Web and WCAG. 1.0. neither set of guidelines

Thanks to Donal for this more comprehensive assessment of the
issues with CHM.  Lest there be any confusion, let me re-iterate
that my own position is that CHM, in and of itself, cannot be
seriously offered as an "accessible" format.  In my own note I
was just finessing any more detailed discussion by pointing at
guideline 11.2.  But as Donal shows, inaccessibility arises on a
number of levels against multiple guidelines.

I also circulated this via the W3 wai-ig list.  There has been a
very vigorous discussion there ... but unfortunately most of it
went immediately off topic!  However, one new point was briefly
flagged that I had not anticipated.  Microsoft have, in recent
years, had a policy of very actively registering software patents
(not yet possible in the EU, but very important internationally).
So, while I have no knowledge of any specific patents to CHM, it
is quite possible that they exist.  If so this could be a
significant chilling factor in development of any tailored
assistive technology to work with CHM.  Indeed, even the
possibility of such patents has a significant chilling effect...

So, my take home message still stands: by all means offer CHM as
a secondary, alternative, option for content - but never
exclusively.  The primary format for this category of material
should be HTML/XHTML (plus CSS) conforming to WCAG (at least
Double-A for preference).  Assuming this is taken on board, then
any more detailed accessibility evaluation of CHM is largely a
red herring.  I actually take this to be the explicit lesson of
what Henry described of the evolution at HP.

Best - Barry.