Re: Graphics contrast - critical principle

> On Dec 8, 2016, at 11:31 AM, Bailey, Bruce <Bailey@Access-Board.gov> wrote:
> 
>> I think we need to define the unit of testing, there needs to be some element on the screen that has to be seen & discerned separately from other elements in order to be understood. 
> 


The Unit of testing for WCAG is the page.    If you try to use something smaller it will fundamentally change everything.

For example, the whole conformance model is based on the fact that there may be inaccessible elements on a page as long as there is an alternate presentation that is accessible.     If you make the  unit of test smaller than the whole page — then the conformance model breaks.   

Now it is more subtle than just this simple statement — but you get the idea.  

Conformance is based on pages — SC apply to elements singly and in combination with the other content on the page.  

So be careful with the term “unit of testing”  so things don’t get confused.    Maybe Unit of testing (is web pages)    and "unit of analysis” is for SC?   or some such? 

g