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Navigating a document

From: Charles McCathieNevile <charles@w3.org>
Date: Wed, 14 Apr 1999 00:02:38 -0400 (EDT)
To: WAI UA group <w3c-wai-ua@w3.org>
Message-ID: <Pine.LNX.4.10.9904132344050.2287-100000@tux.w3.org>
Based on the 31 march document. This is to discharge my renmaining action
item from the last teleconference.

I think we could dramatically reduce the number of checkpoijnts reqiured -
I have come up with the following proposed checkpoints/techniques for 6.2

checkpoint:
P1 Allow the user to navigate among active elements

definition: any element which has some associated event or action -
examples are links, form controls, and elements which trigger events.

checkpoint:
P1 Allow the user to navigate table cells sequentially across a row or up
and down a column. This requirement applies to non-visual browsers, but
the capacity needs to be exported via interfaces (see current 7.2)

Checkpoint:
P2 Allow the user to navigate a document via its structure

Techniques: 
Allow the user to walk a tree of the elements (eg DOM). This would include
navigating from form to form, table to table, navigating (in HTML) all the
headers of a document). There are two ways to go in a tree - up and down
the tree (parent to child) or across (sibling to sibling). Block level
elements in HTML are usually siblings - paragraphs, headings, lists, etc
are siblings of the BODY. XML will generally provide more structure -
second level headings would be children of first level headings, etc.
Table cells are also included here because they are elements, but this is
a P2 checkpoint.

Allow the user to walk an outline tree or "semantic tree"
constructed from an HTML document in which H3 elements are treated as
children of H2 elements, etc.

Notes:
It is possible that the two techniques could be drawn into seperate
checkpoints but I don't really see the need. The only case I can think of
where the second technique would rate as a P2 checkpoint is moving from
cell to cell in columns (which is not supported by DOM) which is P1 in
most cases. Otherwise only one of these techniques is really P2 and teh
other becomes P3. Given the requirement to implement the DOM, supporting
walking of the DOM tree is the obvious choice for implementers, but it is
not the only possible approach. (It is probably more important to
Authoring Tools, where manipulation of the DOM is a standard activity).

Charles McCN

--Charles McCathieNevile            mailto:charles@w3.org
phone: +1 617 258 0992   http://www.w3.org/People/Charles
W3C Web Accessibility Initiative    http://www.w3.org/WAI
MIT/LCS  -  545 Technology sq., Cambridge MA, 02139,  USA
Received on Wednesday, 14 April 1999 00:02:40 GMT

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