Are visible labels required per WCAG 2.0?

I'm starting this thread because I believe there is a need for 
"perceivable" information by all users, including those  who are sighted 
but may have vision impairments, reading impairments, cognitive 
impairments, aging, or are learning about new content or a new 
application. 


There are differing opinions and interpretations on whether visible labels 
are required by WCAG 2.0 on things like form elements, row and column 
headings, and interactive elements (widgets). Often the argument is made 
that when such relationships and labels are visible to one set of sighted 
users, that those relationships and labels can be made to be perceivable 
to assistive technology users as well, but not the other way around.  I 
even advocate as a best practice that most any and all information 
perceivable to an assistive technology user should be made visible to 
sighted users too. 

Some common interactive elements or widgets can sometimes be an exception, 
for example:
        1. do all carousel widgets need a visible label? 
        2. do all expandable/collapsable tree widgets need a visible 
label? 
        3. Once you know what the widget is, do you really want to clutter 
up the visible display with labels?

Some rows and columns in a data table can sometimes be an exception, for 
example: columns in data tables have an implied heading, or a row has no 
row heading (or only one that is implied) because of the type of 
information in that column or row. A column with just dates may have an 
implied heading of "Date", but no visible heading. 

Some form controls can sometimes have an implied label, for example when 
there are 5 radio buttons in a series, with the 1st one labeled Strongly 
Agree, the last one labeled Strongly Disagree One, the middle radio button 
visible labeled "Neutral", but the 2nd and 4th radio buttons are not 
visible labeled because of limited space. 

Many subject matter experts interpret WCAG as not requiring a visible 
label on all form elements, row and column headings, or all interactive 
elements, because many interpret the following from WCAG 2.0 Success 
Criteria:

1.3.3 Info and Relationships says that when a label is presented visually, 
that it also be programmatically determined, but not that is has to be 
presented visibly.

2.4.2 Page Titled does require a page title, and it implies that they be 
"perceivable" to all users when it says: "this success criterion benefits 
all users in allowing users to quickly and easily identify whether the 
information contained in the Web page is relevant to their needs."

2.4.6 Headings and Labels does not require headings or labels. This 
success criterion requires that if headings or labels are provided, they 
be descriptive. ('descriptive' is subjective, which is one reason its 
level AA). Also note that, if headings or labels are provided, they must 
meet 1.3.1. 

4.1.2 Name, Role, Value says that the name has to be programmatically 
determined - not that it has to be visible.


WCAG References and links:
1.3.1 Info and Relationships: Information, structure, and relationships 
conveyed through presentation can be programmatically determined or are 
available in text. (Level A) 

2.4.2 Page Titled: Web pages have titles that describe topic or purpose. 
(Level A) 

2.4.6 Headings and Labels: Headings and labels describe topic or purpose. 
(Level AA) 

4.1.2 Name, Role, Value: For all user interface components (including but 
not limited to: form elements, links and components generated by scripts), 
the name and role can be programmatically determined; states, properties, 
and values that can be set by the user can be programmatically set; and 
notification of changes to these items is available to user agents, 
including assistive technologies. (Level A) 
Note: This success criterion is primarily for Web authors who develop or 
script their own user interface components. For example, standard HTML 
controls already meet this success criterion when used according to 
specification. 


UAAG 1.0 did have Guideline 2 "Ensure that users have access to all 
content, notably conditional content that may have been provided to meet 
the requirements of the [WCAG]
UAAG 2.0 Draft does not seem to have a success criteria to render the 
invisible labels that were added to meet success criteria. 
Is there a gap in the requirements between WCAG and UAAG that 
disproportionately affect sighted users with cognitive disabilities? 

Does anyone have a difffering opinon or interpretation of WCAG 2.0.  Seems 
to me that for better visual preceivability, better cognitive 
understanding, and better interactive expereince that everyone, including 
those using unaided browsers should be able to determine the label of the 
form element,, column or row heading, and label of the interactive 
elements (software widgets)? 
___________
Regards,
Phill Jenkins, 
Accessibility Business Development Executive
IBM Research - IBM Accessibility
ibm.com/able
facebook.com/IBMAccessibility
twitter.com/IBMAccess