some WAI comments on Device Independence

[forwarded to www-archive as a backup for www-di]

The following comments have reached a rough consensus in the Protocols and
Formats Working Group of the W3C Web Accessibility Initiative.  We
recommend them for your consideration as you continue this important work.

Alfred S. Gilman, co-chair
/for W3C/WAI/PF

-- comments follow

1. [policy demand: assert this as a policy principle or please let us
discuss why not] 
Give the user the final say (over all adaptation decisions). 
- "Author proposes, user disposes" is recognized as a principle that takes
precedence [Reference: UAAG Guideline 2, <>].  A
framework for adapting content to delivery contexts must operate in
conformance to this rule.  One of the decisions subject to this policy is
where the user interface particulars get bound a.k.a. the interface gets
adapted.  A service may not be offered only by providing final form content
for a narrowly defined class of delivery contexts or a specific device
model.  This removes too many options from the range of access methods
available to people with disabilities for whom modes that you might not
have thought of are effective and sometimes the only effective modes.
Example 1: Voice browsing services should be available in TTY compatible
form.  Example 2: WAP tailored sites are often more usable, when accessed
using a screen reader, than the parallel baseline site tuned for desktop
visual use. 
- Options of reduced flexibility may be offered _only if_ there are
alternatives, the alternatives include at least one flexible [e.g. WCAG
compliant] option, and the user has [defined URIs for] access to the full
range of options.  [Reference:  XSL FO discussions.

- Hyperlinking is an acceptable means of relating alternative options.
Coverage of user requirements may be by the envelope of the capabilities of
the alternatives in this case.  [Reference: GL consensus item S1 toward a
WCAG 2.0 (work in progress), 
find 'S1' in
- Options should be served with residual flexibility which extends their
applicability at least to the point where the delivery context is clearly
into a regime where another of the available options is superior.

2. [HCI knowledge: can we stipulate this as we all believe this is factual?] 
- All things being equal, a selection from multiple prepared, flexible
options for the binding to concrete interface specifics is expected to
deliver more usability for more users than a single, flexible option will
- The user has better knowledge of what works for them and what does not
than an author trying to prepare an experience for multiple users.  Put
another way, the author probably has good knowlege about optimizing user
experience for many users, but not all users, particularly users with
disabilities where the author is unlikely to be fully conversant with the
factors determining what constitutes a usable or optimal experience. 
- Many users cannot articulate what works for them as principles; they only
know what they find to work and what they find not to work instance by
instance after they have tried them out. 
- Users quite generally prefer not to change the author's presentation or
UI design, and to change it as little as possible where necessary.  Most of
the people using something other than the default presentation or input
binding the author offered are people who need to use something different. 
- When there are many settings associated with adapting a user interface,
the user may not be able to navigate the interface state to an optimum.  In
other words, sometimes one has to be scientific and organized about
exploring the user's usability gradients in order to start with a UI
configuration that is close to their optimum in order for them to be able
to find their way to this UI configuration.  [Reference:

3. Enterprise Integration returns on modeling care:  Modeling well the
service offered to users over the Web will make the user contacts that
happen here more valuable to other processes happening elsewhere in the
business enterprise.  Know your business, and you will be able to serve
your customers well.  And your sibling lines of business. [Reference:
discussions of synergy in the business press, such as in discussing AOL
Time Warner].

4. Look to AIAP as a possible platform for demonstrating capability.  For
your information, the National Committee for Information Technology
Standards in the U.S. has a project underway for an Alternate
user-Interface Access Protocol.  Current working documents include the
definition of a Abstract/Alternate Interface Markup Language (AAIML) whose
purpose is full coverage of the capabilities of a target service (including
product operation) with device independence.  Parties interested in
reviewing the working drafts should ask a committee member or start with
email to <>.

Received on Friday, 23 November 2001 16:33:09 UTC