Reading Systems and presentation of TOC

Dear EPUB 3 CG,
 
I recently demoed a wonderful EPUB 3 title from Macmillan Learning. It is
595 pages and has over 700 entries in the TOC.
 
I believe reading systems should have the ability to expand and collapse
items. Because the navdoc is nested lists, this should be possible. I have
seen one of the reading systems do this.
 
It probably depends on the type of data structure the Reading System
implementor  selects. I think a tree view provides for the ability to expand
and collapse sub-branches of the tree.
 
I don't know exactly where this fits, but it is a general usability issue,
which has more of an impact on users of Assistive Technology like a screen
reader. It just makes it easier  and faster to navigate the TOC. Of course
the content provider needs to deliver the TOC as nested lists, but the RS
needs to provide this functionality.
 
 
Thoughts welcome.
 
Thought this would  be a good post for "Global Accessibility Awareness Day"
(GAAD.
 
Happy GAAD
George
 
 
 
 
 
George Kerscher Ph.D.
-In our Information Age, access to information is a fundamental human right.
Chief Innovations Officer, DAISY Consortium
http://www.daisy.org
Senior Advisor, Global Literacy, Benetech
http://www.benetech.org
President, International Digital Publishing Forum (IDPF) 
http://www.idpf.org
Member of the National Museum and Library Services  Board (IMLS)
http://www.imls.gov
Chair Steering Council Web Accessibility Initiative (WAI), a division of the
W3C 
http://www.w3c.org/wai 
Phone: +1 406/549-4687
Cell:+1 406/544-2466 
Email: kerscher@montana.com