Re: Mechanism Disclaimer

When the WCAG 2.0 working group wrote “a mechanism” needed to be available,   what the working group had in mind was that they AUTHOR made sure that a mechanism was (most probably - because nothing is certain)  available.      That is — if the feature was on most common free browsers - then the author could assume that one was available for the viewer to use - and the author did not need to provide one themselves.    If it did not — or their content was created in such a way - or with such technologies - that the feature in the browsers would not work — then they needed to provide their own mechanism.      For example - if they use HTML then the mechanisms were often there.  If they used something else - where the browser mechanism would not work — then they would need to provide a mechanism in their content to achieve the purpose.  
   

We only turned to (or used) this approach when we already saw the features on public free browsers that worked for say HTML but
if the author chose a technology where the browser features would not work — - then they would have to provide it in their content.   (We would first evaluate if there were easy ways for the author to provide the function themselves in their content before we put such a requirement in) 
if the author created their page in such a way that the feature on the browser would not work — then again the AUTHOR would have to to provide their own mechanism to do this
e.g. if you are requiring reflow for reflowable content (e.g. running text) — if the author decided to fix the width of the page (which would defeat the normal mechanism in the web page) then the AUTHOR had to provide a mechanism to reflow it themselves — OR turn off their fixed width command — OR something else that would allow the reflow.
companies sometimes force a particular browser — so INTRANET pages needed to work with what a company had.  If the company enforced use of a browser did not have this - then the company author had to provide the function in their content for their intranet pages  (low use case)
g



Gregg C Vanderheiden
greggvan@umd.edu