Alternate Versions Conformance Requirement

Why permit alternate versions?

Why does WCAG permit alternate versions of Web pages to be included in conformance claims? That is, why include pages that do not satisfy the success criteria for a conformance level in a conformance claim?

Sometimes, pages use technologies that are not yet accessibility supported. When a new technology emerges, assistive technology support may lag behind, or may only be available to some target audiences. So authors may not be able to rely on the new technology for all users. However, there may be other benefits to using the new technology, e.g. better performance, a wider range of modalities available, etc. The alternate version requirement allows authors to include such Web pages in their web site by providing an accessible alternative page in technologies that are accessibility supported. Users for whom the new technology is adequately supported get the benefits of the new version. Authors who look ahead to future accessibility support can satisfy the success criteria now with the alternate version page, and also work with the other page to build in future access when assistive technology (AT) support is available.
For a variety of reasons, it may not be possible to modify some content on a web page. For instance, it may be critical to include an exact visual copy of a document for legal or historical reasons. The web page may be included in a site but the site owner may not have the legal rights to modify the content on the original page. In order to make the content of such pages accessible, an alternate version must be provided, since the web page cannot be made directly accessible.
Sometimes, the best experience for users with certain types of disabilities is provided by tailoring a web page specifically to accommodate that disability. In such a situation, it may not be possible or practical to make the web page accommodate all disabilities by satisfying all of the success criteria. The alternate versions requirement permits such specialized pages to be included within a conformance claim as long as there is a fully conformant ‘alternate version’ page.

A potential disadvantage of permitting Web pages that do not satisfy the success criteria is that people with disabilities will encounter these non-conforming pages, not be able to access their content, and not be able to find the conforming “alternate version”. A key part of the Alternate Versions provision therefore is that ability to find the conforming page (the alternate version). The conformance requirement that permits alternate pages therefore also requires a way for users to find the accessible version among the alternate versions.

Finding the conforming version

The working group has been wrestling with a couple of questions around this issue.

What techniques are there for finding Accessible Alternatives?
Will these techniques allow the user to find the Accessible Alternative from the non-conformant version if they land on it?
How easy are these techniques for users? Will they all be able to use them?
How easy are these techniques for authors? Will they all be able to use them?

These have been difficult issues because there is little that can be assumed about what a person with disabilities will be able to do with the inaccessible version. In some cases, the person with a disability (PWD) may be able to access part of the page that will help locate the accessible version. In other cases, the PWD may not be able to access any of the content on the non-conforming page at all.

The working group has considered three options for what would be required:

Allowing non-conforming pages only if they can provide an accessible link to the conforming page. The link would need to conform to WCAG. That is, even though the page itself didn’t satisfy the success criteria in a way that is supported by assistive technology, the link itself must be.
Allowing non-conforming pages only when there is a link to the conforming alternate version (as in #1) or if it is possible to find a conforming alternate version of the page by using information from the address (that is, the URI) of the non-conforming page.
Allowing non-conforming pages when #2 is met OR there is a common page that points to both the non-conforming and the conforming page. Not requiring any means to find the conforming page if the user lands on the non-conforming page in any other way.

Exploring each of these in turn:

1. Allowing non-conforming pages only if they can provide an accessible link to the conforming page.

Advantages:
1. To user: This guarantees that the conforming page can be found easily when the user lands on the non-conforming page, in a way that is reliable and easy for users to understand.
2. To author:
Disadvantages:
1. To user:
2. To author: This does not allow content formats that do not provide accessible links, and does not allow for web pages where the author does not have permission even to add a link.
Sufficient techniques might include:
1. G136: Providing a link at the beginning of the nonconforming content that points to an alternate version that does meet WCAG 2.0 at the level claimed
2. G20: Ensuring that the only way to get to an inaccessible version is from a link from the accessible version
3. Using environment variables to ensure that the only way to access non-conforming content is from conforming content (future link)
4. SVR2: Using .htaccess to ensure that the only way to access non-conforming content is from conforming content (SERVER)

2. Allowing non-conforming pages only when there is a link to the conforming alternate version (as in #1) or if it is possible to find a conforming Alternate Version of the page by using information from the address (that is, the URI) of the non-conforming page.

Advantages:
1. To user: It allows users who land on a non-conformant page to find the page given only the information they have from the page and its address.
2. To author: This allows content that cannot support links either technically or due to policy etc. It also allows technologies that are new and not yet supported by assistive technology.
Disadvantages:
1. To user: Not as reliable as option #1. The techniques that use the URI of the non-conforming page to locate that conforming page may be difficult for users to use if they need to explore by hand. There are not yet tools to make it easier for users and some techniques may not be possible for tools. With those techniques where a tool cannot check automatically, users may not realize that an alternate page is available, or may give up before finding the conforming page. Non-conforming pages that could provide an accessible link to the conforming page wouldn’t need to provide direct access.
2. To author: Requires authors to employ some technique that would require more effort and/or services on their server.
Sufficient techniques might include:
Techniques listed in #1 plus the following:
1. Storing the conforming content (or autoforwarding to it) at same URI with .htm or .html ending.
  - This approach allows for the development of user agent functionality that looks for alternatives at the same location as the non-conforming page. At the user's option, such functionality could display alternate versions automatically, alert the user to the presence of alternate versions, or check for alternate versions only on request from the user. It assumes that html files with the same name are accessible alternatives to other file types.
2. Finding the conforming web page by searching the domain using only the root of the filename in the URI of the non-conforming web page or the web page title if that is readily accessible from the non-conforming page.
3. Having a page somewhere in the conformance scope that links to both the conforming and non-conforming pages AND having the site search engine able to find this common page from the root of the filename in the URI of the non-conforming page.
4. Linking to non-conforming pages from the conforming page and including the URIs of non-conforming pages in the content of the conforming page.
5. Using the phrase “alternate version” and the filename of the non-conforming page on the conforming page (so it can be easily found).

3. Allowing non-conforming pages when #2 is met OR there is a common page that points to both the non-conforming and the conforming page.

Advantages:
- To user:
- To author: Provides the author with most freedom. Requires only that a common page exists that points to both. Other techniques can be used but are not required.
Disadvantages:
- To user: When a user reaches a non-conforming page directly (e.g. from a search, or a link in an email, blog, article, other page, etc), there may be no way to find the conforming page. The only way to find the alternate version is if you come to the non-conforming page via the common page that also links to the conforming page.
- To author:
Additional sufficient techniques might include:
Techniques listed in #2 plus the following:
1. Having a page somewhere in the conformance scope that links to both the conforming and non-conforming pages.

How can a person reach a non-conforming page other than by navigating the web site?

One of the differences between options two and three is whether there is a way to find a conforming version of a file when the only information that the user has is the address of the non-conforming version. There are many common ways that users can find themselves in such a situation. Some of these are:

A link is sent in an email. (often stripped and forwarded many times )
A link is provided in an article, newsletter, etc.
A link in a blog or user area.
A link in a flyer.
Links on other (non-conforming) Web sites back to the conforming Web site.
Links in software
Search engine results (where the order is by frequency of click, so the accessible version may be hundreds of items later than the non-accessible version)

For each of the options above, here is what the Conformance Requirement might look like.

#1) Alternate Versions: If the Web page does not meet all of the success criteria for a specified level, then a mechanism to obtain an alternate version that meets all of the success criteria is available from the nonconforming content, and that mechanism meets all success criteria for the specified level of conformance. The alternate version does not need to be matched page for page with the original (e.g. the alternative to a page may consist of multiple pages).

#2) Alternate Versions: If the Web page does not meet all of the success criteria for a specified level, then a mechanism to obtain an alternate version that meets all of the success criteria can be derived from the nonconforming content or its URI, and that mechanism meets all success criteria for the specified level of conformance. The alternate version does not need to be matched page for page with the original (e.g. the alternative to a page may consist of multiple pages).

#3) Alternate Versions: If the Web page does not meet all of the success criteria for a specified level, then a mechanism to obtain an alternate version that meets all of the success criteria can be derived from the nonconforming content or its URI and that mechanism meets all success criteria for the specified level of conformance, or a Web page that includes links to both the nonconforming and conforming content is available within the scope of conformance. The alternate version does not need to be matched page for page with the original (e.g. the alternative to a page may consist of multiple pages).