issue-633 update for today's meeting

The issue 633 branch visible at:

http://rawgit.com/w3c/aria/mck_issue633/aria/aria.html

 

Includes the following updates ready for discussion.

 

1.       The articlefeed description has been rewritten for clarity and to
address most feedback raised in last week's meeting.

2.       The aria-feedappendcount and aria-feedprependcount properties have
been added.

3.       The article role is updated to include support for aria-pposinset
and aria-setsize when in the context of an articlefeed.

4.       The aria-busy state description has been rewritten to clarify
intent and align it with the use described in the articlefeed role
description. 

 

I have NOT finished the following:

1.       Incorporating last week's feedback into the grid role description.

2.       Updating the itemfeed role description to incorporate the
improvements made to the articlefeed description.

3.