Re: definition of the a/aa/aaa levels

right 

Gregg C Vanderheiden
greggvan@umd.edu



> On Mar 27, 2017, at 11:06 AM, David MacDonald <david100@sympatico.ca> wrote:
> 
> Probably a good idea to approach it the way we did in WCAG 2.0, which I remember to be that group members took all those things Bruce mentioned into consideration, proposed a level, and had a big discussion and moved things around based on the interaction of members and stakeholders, then iteratively tried to get consensus, then moved them around based on roadblocks, then came to consensus.
> 
> So I'm fine with using these and other categories as an initial way to try to assign levels, but we should no publish a set of considerations for why they were put there... I think that's a rat hole, from which Gregg is trying to spare us.
> 
> Cheers,
> David MacDonald
>  
> CanAdapt Solutions Inc.
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> On Mon, Mar 27, 2017 at 10:25 AM, Alastair Campbell <acampbell@nomensa.com <mailto:acampbell@nomensa.com>> wrote:
> Hi Gregg,
> 
> That’s good to know. I still think Bruce’s somewhat simpler method is useful for us now though.
> 
> We’re adding many new SC to the mix, having some standard factors for initial placement makes it much easier to then move a few around so that everyone can live with it.
> 
> Cheers,
> 
> -Alastair
> 
> 
> On 27/03/2017, 14:46, "Gregg C Vanderheiden" <greggvan@umd.edu <mailto:greggvan@umd.edu>> wrote:
> 
>     Thanks Bruce
> 
>     As you can see — the levels cannot be defined by those factors (or any factors clearly).  They are some of the factors but not all - and even these do not account for the levels of the SC.
> 
>     We tried to do this in the WCAG 2.0 working group too.
> 
>     The WCAG 2.0 working group that assigned the SC to the levels worked hard to describe the levels — but there was so much involved in the decisions - including the interaction of each SC with the other SC at that or another level — that the language used in the Understanding WCAG 2.0 is the only language that is accurate in describing the way levels were defined.
> 
>     there are simply 3 levels
> 
>     A  = Minimum needed for any conformance.
>     AA =  Better
>     AAA = and Better still   (Noting that some AAA cannot be applied everywhere so level AAA should not be required)
> 
>     Even AAA does not make web pages accessible.  (Even all of the advisory techniques do not)
> 
>     So we can’t define the levels as meaning anything specific.   They are just 3 levels of conformance with no absolute meaning outside of the Guidelines.
> 
>     And the only thing that can be said for sure about why an SC is at any level is that, after considering the factors listed (in Understanding WCAG 2.0 ) the level of the SC was the level that the working group could reach consensus on for that SC.
> 
>     WCAG 2.0 was a total consensus document.    All SC wording and levels had the unanimous agreement of the Working Group.   (NOTE: Consensus does not mean that that is where everyone wanted everything.  It means that, in the end, the SC were worded and placed in a way that  everyone could live with them.
> 
>     So what is in Understanding WCAG 2.0 is the best that could.can be said about the factors that the WG used to place the SC.  We could find no concrete formula to describe their placement and when we tried to use a formula - some ended up in the wrong levels.
> 
>     best
> 
>     Gregg
> 
> 
>     Gregg C Vanderheiden
>     greggvan@umd.edu <mailto:greggvan@umd.edu>
> 
> 
> 
>     > On Mar 27, 2017, at 8:53 AM, Bailey, Bruce <Bailey@Access-Board.gov> wrote:
>     >
>     > On the March 21st call, I took the action item to work on the definition between levels.  This work is posted on the wiki [1] and summarized in this email.
>     >
>     > Based on [2] Understanding Levels of Conformance, I boiled the factors discussed there down to four characterizations:
>     >
>     > Essential:  If the Success Criterion isn’t met, then even assistive technology can’t make content accessible; or there are no workarounds; or the content is blocking.
>     > Easy:  The Success Criterion is not technically challenging to implement and requires only minimal effort.
>     > Invisible:  The Success Criterion imposes only trivial limits on the “look & feel” and/or function of the Web page.
>     > All Content:  It is possible to satisfy the Success Criterion for all Web sites and types of content.
>     >
>     > I then went through each WCAG 2.0 SC and made a yes/no determination for each of those four characterizations. [3]
>     >
>     > There is obviously plenty of room for debate with the above two steps, but assuming it is all reasonably close, I offer the following observations:
>     >
>     > In general, WCAG 2.0 Level A SC are:  either [essential and (easy or invisible)] or [both easy and invisible].  20 of 25 Level A SC are characterized this way.
>     >
>     > There are five Level A SC that are exceptions to the above general rule for Level A.  They are:  1.2.1 Audio-only and Video-only (Prerecorded), 1.2.2 Captions (Prerecorded), 1.2.3 Audio Description or Media Alternative (Prerecorded), 1.3.1 Info and Relationships, and 2.4.1 Bypass Blocks.
>     >
>     > 2.4.1 Bypass Block is an outlier because it is the only WCAG 2.0 Level A SC that is not essential and not [both easy and invisible].
>     >
>     > In general, WCAG 2.0 Level AA SC are not essential.  Only 2 of 13 are essential, namely 1.2.4 Captions (Live), and 1.2.5 Audio Description (Prerecorded).
>     >
>     > In general, WCAG 2.0 Level AAA SC are not possible for all content.  21 of 24 Level AAA SC are characterized this way.
>     >
>     > There are three Level AAA SC that are exceptions to the above general rule for Level AAA.  They are:  1.2.8  Media Alternative, 1.4.6  Contrast (Enhanced), and 3.3.6  Error Prevention (All).
>     >
>     > [1] http://www.w3.org/WAI/GL/wiki/WCAG_2.1_Success_Criteria#Initial_Suggestion_for_Priority_Level <http://www.w3.org/WAI/GL/wiki/WCAG_2.1_Success_Criteria#Initial_Suggestion_for_Priority_Level>
>     > [2] http://www.w3.org/TR/UNDERSTANDING-WCAG20/conformance.html#uc-levels-head <http://www.w3.org/TR/UNDERSTANDING-WCAG20/conformance.html#uc-levels-head>
>     > [3] http://www.w3.org/WAI/GL/wiki/Talk:WCAG_2.1_Success_Criteria <http://www.w3.org/WAI/GL/wiki/Talk:WCAG_2.1_Success_Criteria>
>     >
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