W3C home > Mailing lists > Public > w3c-wai-ua@w3.org > July to September 2000

Re: Scoring Example User Agents, etc.

From: Ian Jacobs <ij@w3.org>
Date: Tue, 05 Sep 2000 18:24:15 -0400
Message-ID: <39B5728F.AD7C3FF@w3.org>
To: "Hansen, Eric" <ehansen@ets.org>
CC: "UA List (E-mail)" <w3c-wai-ua@w3.org>
"Hansen, Eric" wrote:
> 
> To: UA List
> From: Eric Hansen
> Re: Scoring Example User Agents
> 
> Suggestion 1: Determine whether there needs to be any adjustment in
> checkpoints due to the new focus on "mainstream graphical user agents".
> 
> The 1 September 2000 draft focuses in on "mainstream graphical user agents"
> and I presume that this excludes user agents that a specifically or
> exclusively for people with disabilities. This seems consistent with our
> earlier discussion of focusing on "general purpose user agents" and with the
> even earlier decision to focus on "general purpose graphical user agents".
> However, as I have said before, there does seem to be a bit of a mismatch
> between the checkpoints and this scope. For example, as currently written a
> user agent could achieve the triple-A level, yet not even be able to present
> graphics. Specifically, there are no requirements that the user agent be
> able to present any given media type.
> 
> This still seems a bit unusual, especially given that the current definition
> of user agent ("A user agent is software that retrieves and renders Web
> content, including text, graphics, sounds, video, images, and other content
> types."), though I suppose that a more accurate definition of user agent
> would replace the word "including" with the words "such as".)

Ok.
 
> My own concern about this mismatch waxes and wanes. Previous suggestions to
> add checkpoints requiring an ability to present certain media types have not
> been implemented. I mention it now because we may find that by making
> changes that I suggested earlier, we may help solve other problems as well.

I understand that adding requirements for the implementation of 
audio, graphics, and video would be consistent with the direction
we've been moving and would allow us to delete another applicability
provision. Considering your comments below from a different angle:

a) We clearly want the document to apply to user agents that 
   render both visual and audio information. 

b) Would we be satisfied with audio rendering alone or visual
   rendering alone? I am inclined to say yes to both of these 
   cases, as long as information is available to assistive 
   technologies and the claim states which checkpoints are considered
   inapplicable. 


Suppose that the user agent does not have a graphical
user interface and only renders audio content. The following
checkpoints would not apply: part of 2.4, 3.1, 3.3, 3.4, 3.5, 3.9,
4.1, 4.2, 4.3, 4.4, part of 4.5 and 4.6, 4.7, and 10.9.
This means that 12 full checkpoints and parts of 2 checkpoints 
would not apply out of 81 total checkpoints (around 15%). 

Suppose that the user agent does not handle audio. The
following checkpoints would not apply: part of 2.4, 3.2,
part of 4.5 and 4.6, 4.8, and 4.9. 
   
In both cases, add three more inapplicable checkpoints 
if the UA doesn't do speech synthesis.

This is not the definitive list of inapplicable checkpoints,
but I conclude after a cursory review that we've done a pretty
good job at organizing the document and designing requirements
that are independent of content type except when content type
is part of the requirement. I also think that when more than
80% of the checkpoints apply, that's good enough to be a useful
indication of the applicability of the document to the subject
of the claim.

We have not spent much time discussing tactile rendering. I don't
think we would object to a claim of conformance by a user agent
that offered a tactile rendering and user interface in conjunction
with either audio or visual rendering, or both. I don't think 
we intended to allow conformance by a user agent that offered only
tactile rendering, even if the user agent implemented the DOM.

> ========
> 
> Suggestion 2: Gather data to strengthen our understanding of some key
> questions related to assistive technologies, plug-ins, and add-ons, etc.
> 
> The 1 September 2000 draft moves in the right direction by clarifying the
> relationship between the UAAG document and assistive technologies:
> 
> "3.2 Which user agents are expected to conform"
> 
> "Users with disabilities often require more than one user agent for full
> access to the Web. For example, a user might require a graphical desktop
> browser, a multimedia player, and specialized assistive technologies such as
> screen readers, which are useful for controlling speech output and
> refreshable braille display. This document focuses on the accessibility of
> mainstream user agents so that most users with disabilities will have access
> to the Web when using a conforming user agent in conjunction with assistive
> technologies. There are also requirements in this document to make user
> agents more accessible to those users with disabilities who do not require
> assistive technologies for full access."
> 
> This paragraph is helpful and seems to reflect pretty well our current state
> of knowledge. Yet there are ambiguities. The second and first sentences
> imply that a combination of technologies -- "graphical desktop browser, a
> multimedia player, and specialized assistive technologies" are necessary to
> provide "full access". Yet the third sentence seems to indicate that the
> "conforming user agent" was treated as a singular user agent rather than as
> a composite (or combined) user agent. I think that we ourselves need to
> understand better how our document behaves when used under different,
> commonly occurring situations.
> 
> The need for further clarification was highlighted in my own case when I
> realized how unsure I was about the answers to some of the following
> questions.
> 
> a. No DOM Support in Component of a Composite User Agent
> 
> True or False: "It is possible for a user agent that does not implement the
> DOM to be a component of a composite user agent that achieves any of the
> three levels of claim (single-A, double-A, and triple-A)."
> 
> Answer: True (?). I thought that there was going to be some indication that
> checkpoints 5.1, 5.2, etc., _cannot_ be considered inapplicable but I don't
> see them so I give "True" as the correct answer.  I have not examined the
> document fully, but I don't see such a provision.

False.

First, there is no need for an explicit statement that the checkpoints
in question are applicable because all checkpoints are applicable
by default. From section 3.4:

     At each conformance level, the user agent must satisfy 
     each checkpoint required for that level unless:

Four applicability exceptions follow, but I don't believe the DOM
to fall under any of them. Thus, the user agent must satisfy the
checkpoints of guideline 5. The DOM API must be implemented for 
access to all content, however the rest of the (composite) user 
agent is implemented (as modules).
 
> ====
> 
> b. No DOM Support in Singular User Agent
> 
> True or False: "It is possible for a singular (non-composite) user agent to
> not implement the DOM and yet achieve any of the three levels of claim
> (single-A, double-A, and triple-A)."
> 
> Answer: True (?). See answer for "a."

False.

> ====
> 
> c. Text Reader Within Composite User Agent
> 
> True or False: "It is possible for a text reader (e.g., screen reader) user
> agent to be a component of a user agent that achieves any of the three
> levels of claim (single-A, double-A, and triple-A)."
> 
> Answer: True (?).

True.

Now show me the completed checklist that indicates which checkpoints
you consider that the text reader satisfies or helps to sastisfy.
 
> ====
> 
> d. Text Reader in Singular User Agent
> 
> True or False: "It is possible for a text reader (e.g., screen reader) user
> agent to be a singular (non-composite) user agent that achieves any of the
> three levels of claim (single-A, double-A, and triple-A)."
> 
> Answer: True (?), though based on the focus on mainstream graphical user
> agents it would not make sense to analyze a singular user agent of this
> type.


What specifications does text reader implement? Does it communicate
with other software? Does it have a user interface? Does it have
documentation? Is it configurable? As long as these questions apply
to the component, then I believe the requirements apply as well.

Here's another way to ask the question: Should we have a document
that allows Lynx to conform (providing that Lynx implements the DOM)?

> ====
> 
> e. Braille Within Composite User Agent
> 
> True or False: "It is possible for a braille display user agent to be a
> component of a user agent that achieves any of the three levels of claim
> (single-A, double-A, and triple-A)."
> 
> Answer: True (?).
> 
> ====
> 
> f. Braille Singular User Agent
> 
> True or False: "It is possible for a braille display user agent to be a
> singular (non-composite) user agent that achieves any of the three levels of
> claim (single-A, double-A, and triple-A)."
> 
> Answer: True (?), though based on the focus on mainstream graphical user
> agents it would not make sense to analyze a singular user agent of this
> type.
> 
> ====
> 
> g. Advantages and Disadvantages
> 
> Open Ended: "Describe the advantages and disadvantages for the developer of
> a 'mainstream graphical user agent' analyzing their user agent as part of a
> composite user agent that includes one or more of the following: multimedia
> player, Braille display, and screen reader package."
> 
> Answer: Not sure. I think that one thing that must be kept in mind by
> someone answering this question is that the subject of each checkpoint is
> the subject of the claim. This means, for example, that if a composite user
> agent includes a Braille display, then the "user interface" in checkpoints
> such as 1.1, 1.3, 1.5, 2.1, 5.2, 5.4, 5.5, 5.8, 8.7, 10.9, should refer to
> the interface of the Braille display as well as to whatever may be presented
> in other display devices.
> 
> Conclusion:
> 
> I would suggest asking one or more people to score the following user
> agents. If only a few of the following could be done, I might suggest
> focusing on numbers 1, 5, 8, and 11. I think that all these cases would be
> helpful.
> 
> 1. Singular user agent = mainstream graphical user agent
> 2. Singular user agent = multimedia player
> 3. Singular user agent = screen reader package
> 4. Singular user agent = Braille display
> 5. Composite user agent = mainstream graphical user agent + multimedia
> player
> 6. Composite user agent = mainstream graphical user agent + screen reader
> package
> 7. Composite user agent = mainstream graphical user agent + Braille display
> 8. Composite user agent = mainstream graphical user agent + multimedia
> player + screen reader package
> 9. Composite user agent = mainstream graphical user agent + multimedia
> player + Braille display
> 10. Composite user agent = mainstream graphical user agent + screen reader
> package + Braille display
> 11. Composite user agent = mainstream graphical user agent + multimedia
> player + screen reader package + Braille display
> 12. Singular user agent = text-only browser
> 14. Singular user agent = audio-only (telephone) browser
> 15. Singular user agent = audio-and-text (telephone) browser
> *
> I think that by examining the claims that would result from these various
> cases, we would be better able to guide people in including or excluding
> user agents from the analyses.
> 
> The more of these cases we can examine, the better we will be able to
> eliminate bugs and other problems that might now exist in the document.
>
> Without this kind of analysis, I am not sure that we can properly judge the
> impact of our recent decisions to (a) allow composite user agents and (b)
> focus more narrowly on 'mainstream graphical user agents'.
> 
> Examples of results that would be of particular interest might include:
> unexpected increases or decreases in conformance when some kind of component
> is added; unusually high or low numbers of inapplicable checkpoints; higher
> accessibility ratings for non-graphical or specialized user agents than for
> mainstream graphical user agents, etc.
> 
> Even if such results caused no changes to checkpoints, they might result in
> changes how we tell people to make the best use of the UAAG document.
> 
> It seems to me that we need not only (a) example implementations of
> individual checkpoints but also (b) example scorings of user agents
> (singular and composite) that people may want to try to use the guidelines
> to analyze.
> 
> Does this make any sense?

Yes. Refer to previous UA evaluations [1]: IE, Amaya, HPR,
HAL+IE/NS/Opera,
NN, PWWebSpeak, and RealPlayer.

As we wrote then:

  "This review will help us correct weak points of the 
   guidelines and fill in gaps where required."

[1] http://www.w3.org/WAI/UA/Evaluations

 - Ian

-- 
Ian Jacobs (jacobs@w3.org)   http://www.w3.org/People/Jacobs
Tel:                         +1 831 457-2842
Cell:                        +1 917 450-8783
Received on Tuesday, 5 September 2000 18:24:18 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Tuesday, 27 October 2009 06:50:14 GMT