Overview and summary of guideline 3.4
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[INTRODUCTION]

From the lastest internal working draft [1]:
"Layout and behavior of content is consistent or predictable, but not identical. 
[level 2 guideline]" 

There are no level 1 success criteria. 

For level 2 there are three success criteria:
1. key orientation and navigational elements (such as navigation bars) are 
   generally found in one or two consistent locations or their locations are 
   otherwise predictable.
2. where inconsistent or unpredictable responses are essential to the function 
   of the content (e.g. mystery games, adventure games, tests, etc.) the user is 
   warned in advance of encountering them.
3. wherever there are extreme changes in context, one of the following is true:
   a) an easy to find setting, that persists for the site visit, is provided for 
      the user to deactivate processes or features that cause extreme changes in 
      context or 
   b) extreme changes in context are identified before they occur so the user 
      can determine if they wish to proceed or so they can be prepared for the 
      change. 

For level 3 there are two success criteria:
1. user can select a different location for navigation elements in the layout of 
   the page.
2. the content has been reviewed, taking into account common ideas for making 
   content consistent and predictable, applying them as appropriate.



[1. OUTSTANDING AND SUMMARY FOR ISSUES]

In WCAG BugZilla there are the following open issues about these checkpoint:

* Bug 315: Navigation Controls, Submission, and Screen Changes 
  (URL: http://trace.wisc.edu/bugzilla_wcag/show_bug.cgi?id=315)
  The NFB put together a list of guidelines for the web, and one of them seems 
  quite pertinent: "Ensure that menus and other navigation controls can be 
  operated without causing form submission or screen changes". For NFB, there has 
  to at least be some warning to the user, or there has to be some kind of user 
  action required before form submission or screen change.

* Bug 383: misc. editorial suggestions for 3.4 
  (URL: http://trace.wisc.edu/bugzilla_wcag/show_bug.cgi?id=383)
  Harvey Bingham in level 2 success criteria point 1 asks to omit the ambiguous 
  opening use of "Key" followed by "orientation and navigational lements" and 
  suggest to use the word "Important" instead of "Key". He asks also to use 
  consistent "verb first" style for each list item because he said that about 
  half now are passive: ... should be ... (i haven't find passive form now).

* Bug 422: Checkpoint (consistent-behavior) difficult to understand 
  (URL: http://trace.wisc.edu/bugzilla_wcag/show_bug.cgi?id=422)
  Kynn Bartlett don't understand what this checkpoint is trying to say 
  (consistent-behavior). It refers to Aug. 2003 and I hope that now Kynn 
  understand it :)

 * Bug 443: 3.4 wording does not seem testable
  (URL: http://trace.wisc.edu/bugzilla_wcag/show_bug.cgi?id=443)
  Cynthia, Kerstin and Wendy wrote: "In particular, the current wording does not 
  seem testable. Words such as, "key," "consistent," "predictable," 
  "inconsistent," and "unpredictable" are subjective. There seems to be overlap 
  with other checkpoints. Success criterion 1 seems to relate more to navigation 
  mechanisms. Success criterion 2 seems to relate more to custom interfaces 
  (4.3). "Extreme changes in context" is a slippery term that seems to refer 
  primarily to pop-ups and to content changes that occur away from the current 
  point of focus. The Additional Notes are littered with "similar," "same," 
  "likely," and "familiar" however in some cases appear to be more testable. The 
  idea of "user interface components" only seems to show up in the Additional 
  Notes and should be moved up to required success criteria.

* Bug 471: does checkpoint require unique layout for each page? 
  (URL: http://trace.wisc.edu/bugzilla_wcag/show_bug.cgi?id=471)
  Tina Holmboe tell suggest to put as a required point (Level 1?) unless WCAG 
  2.0 REALLY requires all sites to avoid having identical layout from page to 
  page - which it doesn't, when reading the criteria.

* Bug 496: identification of context changes, wording suggestion on checkpoint 
  (URL: http://trace.wisc.edu/bugzilla_wcag/show_bug.cgi?id=496)
  Greg Gay writes that an extreme change can be identified after the change has 
  occurred, such as a "close new window" link as the first feature of a popup 
  window, or presenting a feedback message after server side redirecting a user 
  from the content editing screen to the content display screen when editing is 
  completed. For him guideline should read "..., but not necessarily identical".
  It difference from the actual that is "..., but not identical".

* Bug 514: make best practices parallel and expand examples
  (URL: http://trace.wisc.edu/bugzilla_wcag/show_bug.cgi?id=514)
  Joyce Tikalsky refer to the example 2 and example 3. For example 2, from a 
  usability standpoint, some designers suggest avoiding arrows before links 
  because symbols don't give users enough information about the result of 
  clicking the symbol. Maybe just text, such as, "[OPEN THIS LINK IN A NEW 
  WINDOW.]" would be sufficient, right after the link, unless a page is loaded 
  with many links of this type. For example 3, that regard the use of the "back" 
  buttons, so many nonfunctional Back buttons appeared with the emergence of 
  .jsp and .asp pages that he wondered if nonfunctional Back buttons might not 
  be easily controlled  through code in some languages. Perhaps an expert in 
  those languages has confirmed this example.

* Bug 570: Layout is style issue, not accessibility
  (URL: http://trace.wisc.edu/bugzilla_wcag/show_bug.cgi?id=570)
  The U.S. Access Board writes: This is good advice for any webpage design but 
  is not an accessibility issue as much as it is a style issue.

* Bug 703: avoid giving the impression that 3.4 SC only applies to things outside 
  primary content 
 (URL: http://trace.wisc.edu/bugzilla_wcag/show_bug.cgi?id=703)
  Greg Lowney in Point 1 Level 2 success criteria recommend saying something like 
  "(such as navigation bars, page numbers, and section titles)" to avoid giving the
  impression that we're only referring to things outside the primary content.
  
* Bug 704: inline warnings vs. user agent features
  (URL: http://trace.wisc.edu/bugzilla_wcag/show_bug.cgi?id=704)
  Greg Lowney: "Whenever there are extreme changes in context,one of the following 
  is true." In-line warnings and options to deactivate are good, but it seems like 
  UA could also handle this in most cases, such as: letting the user adjust whether
  they want to allow, block, or be asked how to handle pop-ups; notifying the user
  when a page transition makes significant changes to the page layout; identifying
  links that will pop up a new window or go to a different site; etc.

* Bug 705: similar, but not identical
  (URL: http://trace.wisc.edu/bugzilla_wcag/show_bug.cgi?id=705)
  Greg Lowney notes that it's also good for separate sections to be easily 
  distinguishable, which implies not using identical appearance; distinct visual 
  elements such as colors or graphics will help readers orient themselves, keep in 
  mind which section they are in, and avoid mistaking similar pages.

* Bug 706: is there a way to make this criterion have more impact?
  (URL: http://trace.wisc.edu/bugzilla_wcag/show_bug.cgi?id=706)
  Point 2 of Level 3 success criteria ("the content has been reviewed, taking into
  account..."). Isn't there some way that this criterion could be made to have some 
  impact or benefit? I'm afraid that, as it is, criteria phrased this way will just
  be a checkbox that can be checked without anyone doing anything! Perhaps, to have
  some benefit, the web site could post a review of its usability and rationale for
  their decisions to avoid making improvements. Something? Anything? (Greg Lowney)

* Bug 707: example 3 doesn't make a recommendation - seems like a UA problem
  (URL: http://trace.wisc.edu/bugzilla_wcag/show_bug.cgi?id=707)
  Greg Lowney refer to example 3: "frames that do not track history making the back 
  button behave unexpectedly". This doesn't describe a recommendation; is it simply 
  to avoid frames? (Again, it seems like UA should be able to solve this problem 
  without changes to Web sites.)



[2. PREVIOUSLY PROPOSED SOLUTIONS]

* Guideline
  The proposal in [Bug 496] are to change modifying the actual with ", but not 
  *necessarily* identical". The new text will become: "Layout and behavior of 
  content is consistent or predictable, but not necessarily identical". Adding 
  the word "necessarily" can let the developers to use also identical layout and 
  behaviour. [Bug 705] tells instead that identical layout and behavior could
  not be good for avoid mistaking similar pages. In [Bug 471] the proposal is 
  to define this guideline as "requested" (Level 1?).

* Level 1 Success criteria for guideline 3.4
  [No level 1 proposal]

* Level 2 Success criteria for guideline 3.4
  1. From [Bug 383], proposal to change the word "key" with "important". 
     [Bug 703] suggest to apply "(such as navigation bars, page numbers, 
     and section titles)" instead of "(such as navigation bars)"
  2. In the same message source for [Bug 705] [2] there is a request of clarify 
     about "when inconsistent of unpredictable responses [...] the user is warned 
     in advance of encountering them" (open a new bug for this point?)
  3. [Bug 704] tell that in-line warnings and options to deactivate are good, 
     but it seems like UA could also handle this in most cases. So, could this
     be an UA accessibility requirement?
  4. Possible new success criteria? [Bug 315] "Ensure that menus and other 
     navigation controls can be operated without causing form submission or screen 
     changes"

* Level 3 Success criteria for guideline 3.4
  1. [No proposal]
  2. From [Bug 706] there is not a proposal but a request of clarify the method
     for "common ideas for making content consistent and predictable". With the
     notes [3] i think that this bug can be closed.

* Benefits of guideline 3.4
  [No proposal]

* Examples of guideline 3.4
  1. [No example 1 proposal]
  2. [Bug 514] ([OPEN THIS LINK IN A NEW WINDOW.] text instead of icon with an 
     arrow).
  3. [Bug 514] (nonfunctional Back buttons that can be controlled by programming 
     code).  Another solutions is inside the [Bug 496] (a "close new window" link 
     as the first feature of a popup window, or presenting a feedback message after 
     server side redirecting a user from the content editing screen to the content 
     display screen when editing is completed). This last proposal can be 
     integrated for let the user to return to the previous page (back) closing the 
     new popup window. And, as suggested by [Bug 707] is it simply to avoid frames?
  4. [No example 4 proposal]



[3. NEW PROPOSED SOLUTIONS]

* Guideline
  Agree with [Bug 443] (Words such as, "key," "consistent," "predictable," 
  "inconsistent," and "unpredictable" are subjective) and following the request 
  of bug [Bug 496] (", but not *necessarily* identical"). My proposal is to make 
  more "clear" the language used for this guideline and apply a clearification 
  of the scope of it Using the word "coherent" (synonym of consistent) and 
  deducible (synonym of predictable) make more clear that the developer must 
  create layout an behaviour coherent and that must be deducible. Also adding 
  the word "necessarily" help to apply the guidelines in other web contents, 
  like - for eg. - PDF files. The actual text:
  "Layout and behavior of content be is consistent or predictable, but not 
  identical. [level 2 guideline]"
  could be change with:
  "Layout and behavior of content is coherent or deducible, but not necessarily 
  identical. [level 2 guideline]"
  Group need to discuss about [Bug 705] (change layout and behavior for avoid 
  mistaking similar pages)

* Level 1 Success criteria for guideline 3.4
  Applying [Bug 383] and [Bug 703] the new version will be: 
  "Important orientation and navigational elements (such as navigation bars, 
  page numbers, and section titles) are generally found in one or two consistent
  locations or their locations are otherwise predictable".

* Level 2 Success criteria for guideline 3.4
  [No level 2 proposal]

* Level 3 Success criteria for guideline 3.4
  [No level 3 proposal]

* Benefits of guideline 3.4
  [No proposal]

* Examples of guideline 3.4
  1. [No example 1 proposal]
  2. The example - IMHO - create a ripetitive text. In this case is best to 
     suggest at the developer to group the links and inform that all the links 
     inside this group will open in a new window. Also use the image and not 
     direcly the text can create problems for the low-vision people that can 
     have difficulty to see well the arrow.
     Regarding the web, the browser producers are deciding to remove the "open" 
     method for the "window" object and XHTML 1.x has removed the "target" 
     attribute. So, why don't suggest to not use new windows?
  3. As described well in [Bug 514], the "back" button problem for new window 
     can be covered over programming techniques (for eg. the session cookies 
     keep track where an user goes and can be used for give information about 
     the page).  
  4. [No example 4 proposal]
  5. Following the suggestion of [Bug 496] i suggest this new example. 
     Example 5. Options for close pop-up window.
     A "close new window" link is provided as the first feature of a popup 
     window. In alternative, present a feedback message after server-side 
     redirecting a user.



[4. DEPENDENCIES BETWEEN GUIDELINES]

(1.5) Structure has been made perceivable through presentation
(2.4) Mechanisms have been added to facilitate orientation and movement in 
      content.



[5. ASSUMPTIONS]

I assume that the working group think about this guidelines expecially for the 
web pages. For eg. without adding the possibility to have identical layout and 
behavior we make difficult the possibility to apply some kind of web content 
like e-books readable on-line (is difficoult that a book change layout and 
behavior for every page...).



[6. RATIONALE]

This guideline is important because let people to have uniformity in the web 
site browsing, like reading a book: having a web site well formatted with same 
layout and navigation facilities help all people, expecially people with 
cognitive disability, to understand their position inside the web site be sure 
that they find the same layout with the same functionality in the same position 
in all (or in part of) the web site.


Roberto Scano (IWA/HWG)
http://www.iwanet.org - http://www.hwg.org
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[1] http://www.w3.org/WAI/GL/WCAG20/WD-WCAG20-20031117.html
[2] http://lists.w3.org/Archives/Public/public-comments-wcag20/2003Nov/0003.html
[3] http://www.w3.org/WAI/GL/WCAG20/WD-WCAG20-20031117.html#consistent-predictable-notes