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Responses to RealNetworks issues raised during third last call of UAAG 1.0

From: Ian B. Jacobs <ij@w3.org>
Date: Thu, 05 Jul 2001 12:45:34 -0400
Message-ID: <3B4499AE.76A7242D@w3.org>
To: robla@real.com
CC: w3c-wai-ua@w3.org

The User Agent Guidelines Working Group (UAWG) has almost
finished resolving the issues raised during the third last call
review of the 9 April 2001 UAAG 1.0 [1]. 

This is the UAWG's formal response to the issues you raised on behalf
of RealNetworks, which have been logged in the Working Group's issues
list [4].  Some of these issues were raised in a discussion with Ian
Jacobs, others were part of a formal review.  The UAWG's resolutions
and other editorial suggestions have been incorporated into the 22
June 2001 draft of the UAAG 1.0 [5].

Please indicate before 19 July whether you are satisfied with the
UAWG's resolutions, whether you think there has been a
misunderstanding, or whether you wish to register an objection.
If you do not think you can respond before 19 July, please let me
know.  The Director will appreciate a response whether you agree
with the resolutions or not.

Below you will find:

 1) More information follows about the process we are following.
 2) A summary of the UAWG's responses to each of your issues.

Note: Where checkpoint numbers have changed, I indicate the mapping to
the 22 June 2001 draft.

Thank you,

 _ Ian

1) Process requirement to address last call issues

Per section 5.2.3 [2] of the 8 February 2001 Process Document, in
order for the UAAG 1.0 to advance to the next state (Candidate
Recommendation), the Working Group must "formally address all
issues raised during the Last Call review period (possibly
modifying the technical report)." Section 4.1.2 of the Process
Document [3] sets expectations about what constitutes a formal

  "In the context of this document, a Working Group has formally
  addressed an issue when the Chair can show (archived) evidence
  of having sent a response to the party who raised the
  issue. This response should include the Working Group's
  resolution and should ask the party who raised the issue to
  reply with an indication of whether the resolution reverses the
  initial objection."

If you feel that the response is based on a misunderstanding of
the original issue, you are encouraged to restate and clarify the
issue until there is agreement about the issue, so that the
Working Group may prepare its substantive response.

If the response shows understanding of the original issue but
does not satisfy the reviewer, you may register a formal
objection with the Working Group that will be carried forward
with the relevant deliverables. There are currently two
objections that the UAWG will carry forward with the document in
a request to advance to Candidate Recommendation. Each concerns
the priority of checkpoint 12.1, one that the priority should be
lowered, the other that the priority should be raised. There are
additional supporters of each position.

  Phill Jenkins:
  Gregory Rosmaita:

[1] http://www.w3.org/TR/2001/WD-UAAG10-20010409
[2] http://www.w3.org/Consortium/Process-20010208/tr.html#RecsCR
[3] http://www.w3.org/Consortium/Process-20010208/groups.html#WGVotes
[4] http://server.rehab.uiuc.edu/ua-issues/issues-linear-lc3
[5] http://www.w3.org/TR/2001/WD-UAAG10-20010622/

2) Issues you raised and responses

Raised during discussions between RealNetworks and Ian
Summary of issues:

Issue 495: 2.4, 3.5, 4.4: Don't require buffering of lost packets

Resolution: The UAWG agrees with the reviewer: user agents are not
required to buffer "lost packets" due to a user-initiated pause.  We
will clarify in the document that for some live presentations, there
may be information loss when pause happens for 2.4, 3.5, and 4.4.

Note, however, that for checkpoint 3.3 (toggle blinking/animated
text), that the user agent must not drop packets.

Issue 496: 2.4: How useful in heavily interactive presentations? 

Real Networks: "In many situations, dynamic content may be accompanied
by banner advertisements, for instance. Imagine a presentation where
the top of the presentation is occupied by a series of eighty banner
ads, one after the other, each lasting 30 seconds. It would seem that
pausing the presentation every thirty seconds to allow for user input
(for ads or some other content) would not make for a very positive
user experience. In short, dynamic content with frequent and numerous
opportunities for interaction would not be very usable if paused so
frequently. Consider also a stock ticker, where each symbol is a link
to that company's home page (or data about that company). How would
2.4 work in this case?"

Resolution: No change to the document. The UAWG agrees for that some
presentations, this functionality may not be useful. However, it is
expected to be useful for many types of presentations. In the case of
a stock ticker, for example, the author should provide alternative
static access to all of the stock symbols.

Issue 497:  2.4: What is scope; what must the user agent pause? 

Issue summary: Does the requirement to pause presentations apply to
all content, even if not synchronized?

Resolution: No change to the document.  Checkpoint 2.6 covers the case
of synchronized content: if one piece of content is paused, the rest
must be as well (to respect synchronization). For non-synchronized
content, the user agent might pause everything or might not pause
unrelated content. The UAWG presumes that both streams will be
available at another time, and if not, the user must be able to choose
which is preferred.

The following recommendation appears in the note after 2.4:

  "Per checkpoint 2.6, when the user pauses one piece of a
  synchronized presentation, the user agent should pause all of the
  pieces (whether they are rendered in the same or different

Issue 498: 2.1, 2.2, 8.1, 8.2: Conformance for some but not all formats 

Issue summary: It was not clear in the last call draft whether a UA
had to satisfy the requirements of UAAG 1.0 for every format
implemented, or whether some formats could be used to satisfy the
requirements and others be outside of a conformance claim for the same
user agent.


  - The user agent is not required to conform for *all* formats. 

  - A claim should include information about which formats are
    implemented for the purposes of conformance.

  - The claim should include information about which APIs are
    implemented for the purposes of conformance.

Issue 499: 3.3: Relationship between streaming text and animated text 


 - Animation and streaming are independent. Streaming is a content
 delivery technique while animation is a content presentation

 - UAAG 1.0 requires that animated content be available in
   non-animated form. This would include streaming content.

Issue 500:  4.6: When captions are positioned with constraints, 
how does override work? Can captions be positioned in a
separate viewport? 

Resolved: This checkpoint may be satisfied by putting captions in a
separate viewport with some constraints. Checkpoint 4.6 has been
modified in the 22 June draft to read:

  1.For graphical viewports, allow the user to position captions with
  respect to synchronized visual tracks as follows: if the user agent
  satisfies this checkpoint by using a markup language or style sheet
  language to provide configuration or control, then the user agent
  must allow the user to choose from among at least the range of
  positions enabled by the format otherwise the user agent must allow
  both non-overlapping and overlapping positions (e.g., by rendering
  captions in a separate viewport that may be positioned on top of the
  visual track).

  2.In either case, the user agent must allow the user to override the
  author's specified position.

  3.The user agent is not required to change the layout of other
  content (i.e., reflow) after the user has changed the position of

  4.The user agent is not required to make the captions background
  transparent when those captions are rendered above a related video

Issue 501: 10.9: What is scope of position indicator? 

RealNetworks comment: Imagine a presentation with 80 audio clips in a
row (this could be done in SMIL with a element). Should the position
indicator account for all 80? Or each one, one at a time? I wouldn't
want the user agent to have to go out to the Web to get duration
information about all 80 clips in advance in order to build a
proportional position indicator. Instead, I think it would be
reasonable to display in that case something like "First of 80 clips,
20% of first clip".

 - UAAG 1.0 will not require any particular granularity for
   position indication.

 - The technique suggested by RealNetworks has been added
   to the document.

Raised during formal review
RealNetworks review comments:

Issue 506: 4.1, 4.2, 4.3: How does one value work when different 
components control different content? 

Issue summary: How does a global configuration requirement work when
different modules render and provide control over different types of


 - The definition of "global configuration" now reads:

   "A global configuration is one that applies across elements of the
   same Web resource, as well as across Web resources. A global
   configuration may be implemented by more than one setting (e.g.,
   per component of the user agent). For instance, when a user agent
   consists of a browser that renders HTML and a plug-in that renders
   SVG, to satisfy the global configuration requirements of this
   document, the browser may provide one setting and the plug-in

Issue 507: 4.3: If the format does not provide a way to
specify a global background color, does the checkpoint 
apply if user agent can specify background color 
on a region-by-region basis? 

Resolution: Checkpoint 4.3 applies to all regions (same for 4.2,
4.2). The format may not allow background to be set at a global level,
but it doesn't matter to the user: the background color has to be
"color X" everywhere. Thus, the user agent may have to satisfy this
requirement by setting the background color on all regions.

Issue 508:  4.5: Require clarification - is fast playback required, 
or just the ability to jump forward in time? 


 - Fast playback is not required. The requirement is for the
   ability to jump forward in time (either serially or discretely).

Issue 509: 6.1, 6.2: P1 to provide access to content (e.g., in 
raw form), DOM either P2 or alternative 

Resolution: The UAWG does not agree with the reviewer, and maintains
the DOM requirements as P1 requirements. To address this issue, the WG
invited assistive technology developers to a special teleconference
dedicated in part to this question. A summary of this teleconference
is available:

At this teleconference, there was clear consensus that AT developers
found the DOM requirement important and useful, and await

The UAWG points out that raw access to content is insufficient as a
technique because it does not allow an assistive technology to track
changes in the browsing session incrementally; any change to content
requires the AT to reparse content and this makes tracking point of
regard very difficult.

The UAWG also points out that while cost and implementation burden are
considerations, they are secondary to user needs in establishing
requirements for this document. The UAWG will further address cost and
implementation issues in Candidate Recommendation.

Issue 510: Conformance: How to observe OS conventions when 
building a cross-platform user agent? 


 - The UAWG maintains that in general, it is a P2 requirement
   to observe operating environment conventions because:

   a) Conventions themselves are an accessibility issue (e.g.,
      inconsistency in the user interface may cause problems
      for users with cognitive disabilities).

   b) Conventions are also important to interoperability with 
      assistive technologies.

 - For some specific important cases, UAAG 1.0 includes
   P1 requirements for following operating environment

    * 6.6: The UAWG considers that the conventional APIs for
           the keyboard must be implemented due to interoperability
    * 7.1, 7.2: These are P1 because they are important for
           interoperability and keyboard input consistency.

 - The UAWG concludes that, while cross-platform design is certainly
   beneficial to developers, those advantages do not override the
   needs of users, who use a single platform at a time, and who need
   consistency and interoperability on that platform.

Ian Jacobs (ij@w3.org)   http://www.w3.org/People/Jacobs
Cell:                    +1 917 450-8783
Received on Thursday, 5 July 2001 12:48:28 UTC

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