3.10 Provide a linear alternative for parallel, word-wrapped columns of text
WAI checkpoint 10.3
Full WAI text: "Until user agents (including assistive technologies) render side-by-side text correctly, provide a linear text alternative (on the current page or some other) for all tables that lay out text in parallel, word-wrapped columns."
Content which is presented as side-by-side text, laid out in parallel columns like a newspaper page should also be presented without the columns so users of older web browsers or assistive technologies, which can't cope with columns, can read the content. This "no columns" or linearised version could be provided on the same page as the version with columns, or it could be presented on another page.
A user agent is a piece of software for accessing Web content. User agents could be desktop graphical browsers, text browsers, voice browsers, mobile phones, multimedia players, plug-ins, and some software assistive technologies used in conjunction with browsers such as screen readers, screen magnifiers, and voice recognition software.
In the context of information technologies, assistive technologies help people to use computers, websites, public access terminals where otherwise, they couldn't. Examples of assistive technologies are screen readers, hearing aids, special keyboards, pointing devices or other technical solutions which allow the user to provide an input and or receive an output from a computer.Not all user agents or assistive technologies automatically allow users to linearise columns. Until such time as they do, you must provide the linear alternative.
Some assisitive technologies, especially older ones, don't recognise columns and can't present the information in a way that makes sense to the user. They will often read left to right, top to bottom down the page and will fail entirely to separate the columns. Imagine listening to someone read a newspaper page in this way; the output is a confusing mish-mash of sentence fragments which do not in make any sense to the listener. All context and meaning is lost.
Assistive technologies tend to be expensive and learning to use them can also demand a considerable effort of the user which discourages users from upgrading them on a routine basis, as opposed to standard browsers which are often free of charge and comparatively easy to use. This is one reason why it is important to develop sites with older technologies in mind.
Directions and Techniques
Ensure that the content of alternative, linearised versions is up to date
If you provide an alternative version of a web page, or part of a web page, make sure that the content is equally up to date on both versions. This is not a problem with database driven sites but will take some effort on "static" HTML sites.
Provide a meaningful link title to the alternative version and provide it high on the page
Ensure that the link title which takes the user to the alternative version is easy to get to and that it makes sense when read out of context.
"Linearised" does not mean "text only"
Linearised versions of web pages are often presented as "text only" versions. This happens when developers mistakenly assume that only screen reader users avail of the alternative version. Linearised versions may be used by people who prefer the layout either because they like it or because it suits their browser. Just because a browser can't cope with tables does not automatically imply that it can't also cope with images. Supporting images are helpful and should be included wherever possible.
How you could check for this:
Determine if a linearised version is required
Run a sheet of paper down the page and read the page line by line, left to right. Ignore columns - including navigation links which could be presented in a column at the left or right of the page. If the content does not make sense when read this way, a linearised version is required.