Information on DHTML for telecon today

I know most people will not have time to review this information before the
telecon.  But, I though it would be a good reference during the telecon to
refer to when discussing DHTML.
Jon


A. Provide information about the content and structure of a document

User agents need to support users who cannot use information on the display to
identify elements, relationships and actions in a document. Users need to be
oriented to they types of information and actions that are available on a
page.
If users cannot orient themselves to the types of elements in a document,
users
who are blind, have low vision, some types of learning disabilities, or any
user
who cannot or has chosen not to view the authors representation of information
will have incomplete knowledge of the content of the document. 

Techniques  
1. Provide a mechanism for assistive technologies to identify which elements
have associated DHTML events. [+P1] [+Torientation-dhtml] 
2. Render information about elements and DHTML events when certain events
occur
(e.g., focus, hover, etc.). [+P2] [+Torientation-elements] 

B. Allow keyboard navigation and activation of DHTML events

Dynamic HTML techniques are providing capabilities to make Web documents
application interfaces that allows authors to progamatically change the
information rendered to the user and respond to event created by the user. 

There are several types of uses of DHTML:
1. Data verification or translation in form based document inwhich events are
invisible to the user. 
2. Data verification or traslation in a form based document inwhich events
dynamically change the informaton resented to the user. 
3. Implementation of help features (mostly uses mouse over events), including
things like popup windows. 
4. Application interfaces that dynamically change content redenred to the user
based on user actions or changes document state (i.e. document data
information
changes). 
5.  Applications that use events as decoration to improve the visual or
auditory
effects of a page. 
6.  Documents that use a combination of these techniques. 

Some uses of Dynamic HTML techniques are therefore invisible to the user, but
more likely DHTML events will change content based on user actions. 

The basic issues for accessibility are threfore:
1. Identifying which elements have events associated with them and what
types of
event the element responds to. 
2.  Providing a means for the user to activate the event. 
3.  Providing information back to the user on changes in document content 

Technques:  
1. Sequential keyboard access to explicit events assoicated with an element.
[+P1][+Tnav-dhtml-sequential] 
2. Direct keyboard access to explicit events associated with an element.
[+P1][+Tnav-dhtml-direct] 
3. Keyboard equivalents for simulating mouse explicit events.
[+P1][+Tnav-dhtml-simulate] 

Jon Gunderson, Ph.D., ATP
Coordinator of Assistive Communication and Information Technology
Division of Rehabilitation - Education Services
University of Illinois at Urbana/Champaign
1207 S. Oak Street
Champaign, IL 61820

Voice: 217-244-5870
Fax: 217-333-0248
E-mail: jongund@uiuc.edu
WWW:    http://www.staff.uiuc.edu/~jongund
        http://www.als.uiuc.edu/InfoTechAccess