Re: Survey ready on canvas proposal

On Feb 22, 2010, at 2:23 PM, Michael Cooper wrote:

> There is a one-question survey ready on the proposal from the canvas  
> sub-team:
>
> http://www.w3.org/2002/09/wbs/44061/20100225_canvas/
>
> Please take a moment to provide your view. While the survey will be  
> open until Thursday, if you can, try to provide your input by the  
> end of Wednesday in order to allow input to be incorporated prior to  
> Thursday discussions.

I'd like to ask for a clarification on something that is not fully  
clear to me from the proposed spec changes. If adom is not set, are  
user agents forbidden to expose the children of <canvas> to assistive  
technologies? Or is it meant as a hint that they don't need to, and  
the contents may not meet the stated requirements?

Specifically, this is the sentence that is not totally clear to me:

  "The default value for adom is false to indicate that the canvas  
subtree is only used as fallback content and may not be used as an  
accessible DOM subtree representation of what is drawn on canvas."

Is the "may not" in that sentence meant to be a UA requirement, and is  
it meant to be mandatory or optional? Does "used as an accessible DOM  
subtree representation of what is drawn on canvas" apply to any form  
of exposing the content to AT?

Regards,
Maciej