The position in the UK, unlike many countries, is relatively clear. Private and public sector Websites face accessibility obligations under the Disability Discrimination Act (DDA). Part III of the DDA (which came into force on 1st October 1999 ) refers to the provision of goods, facilities and services. The Code of Practice, which specifically mentions websites, can be downloaded in its entirety from the DRC website.
The most relevant quotes from the Code of Practice are: * 2.2 (p7): “The Disability Discrimination Act makes it unlawful for a service provider to discriminate against a disabled person by refusing to provide any service which it provides to members of the public.”
To make 'reasonable adjustments' in circumstances in which the effect of that failure is to make it impossible or unreasonably difficult for the disabled person to make use of any such services. (19(1)(b))
Doesn’t require the traditional "submit data — retrieve web page" methodology
more streamlined applications that require less processing and data transmission because entire web pages do not need to be generated for each change that occurs
Ajax – (“b ecause something is happening here / But you don’t know what it is / Do you, Mister Jones?” )
There doesn't appear to be any reliable way to notify screen readers of an update in the DOM.
Gez Lemon has posted a hack for Jaws 7.1 that improves upon the way it updates its virtual buffer
Progressive enschmancement and Disgraceful degredation
Graceful Degredation – creates pages for the latest browsers that would also work well in older versions of browser software
Progressive enhancement uses web technologies in a layered fashion that allows everyone to access the basic content and functionality of a web page, using any browser or Internet connection, while also providing those with better bandwidth or more advanced browser software an enhanced version of the page.