The principle of inclusion in web accessibility
Full and effective participation and inclusion in society' is one of the general principles that underlie the Convention on the Rights of Persons with Disabilities and each one of its articles. The goal of inclusion signifies that there is an obligation to create environments that provide access to all aspects for all people on an equal basis.
The concept of inclusion is linked with "universal design", which is defined in the Convention as "the design of products, environments, programmes and services to be usable by all people, to the greatest extent possible, without the need for adaptation or specialized design".
Therefore, every effort should be made to create universally accessible pages. The use of alternative, accessible versions should be kept to a minimum, as a last resort.
WAI Definition (Checkpoints 6.2 and 11.4)
If, after best efforts, you cannot create an accessible page, provide a link to an alternative page that uses W3C technologies, is accessible, has equivalent information (or functionality), and is updated as often as the inaccessible (original) page.
Ensure that equivalents for dynamic content are updated when the dynamic content changes.
If an accessible page cannot be created, provide a link to an alternative, accessible page which uses W3C technologies, containing the same information (or functionality), and is updated as often as the inaccessible (original) page. The United Nations strives to have an inclusive approach for disabled persons. Therefore, every effort should be made so that the majority of pages are accessible. The use of an alternative, accessible page should be reserved to specific cases where the content cannot be made accessible directly.
As dynamic content is updated, ensure that the “equivalent” for the dynamic content is updated simultaneously.
When content is delivered with technologies that may not be accessible to all, it is important to offer an alternative, accessible presentation of this content, which is kept up-to-date so that users do not access outdated information.
Provide a clear link to alternative version(s) at the top of each page
Providing the link at the top of the page means that the user does not have to wade through inaccessible content to find the alternative version. You should also provide a link to allow the user to navigate directly back to the original version.
Use scripts to automatically detect different browsers and present appropriate versions of web pages
A 'browser detect' is a script which can detect the type of browser used by a visitor to a site. If a browser detect is used in combination with alternative versions, it is possible to present the user with a version of the page which works well in their browser. Note that it is not possible to detect if the user is using a screen reader because it is not a browser.
Use server-side scripts to generate alternative pages on demand
Server-side scripts, such as Java servlets, or PHP, can be used to create alternative presentations of a page if the user requests one through the browser. The benefit of providing alternative pages in this way is that there is no requirement to maintain different 'versions' of a website, which reduces the maintenance effort and ensures that up-to-date content is delivered to the user, regardless of the version selected.
Check the content of the alternative page.
The content of the alternative page is equivalent to the content of the dynamic page.