The WCAG guidelines advise using the clearest and simplest language appropriate. Perhaps this guideline is taken the least seriously from all WCAG, but for some, its lack of implementation can be a true accessibility hazard.

Many people require clear and simple language. In this article I want to focus on one disorder where the use of unclear language prevents their participation in many aspects of society. Semantic Pragmatic Disorder (semantic = the relationship between words and their meaning; Pragmatic = making language work in context) or SPD, this is a communication disorder. It is often associated with autism, but is often a disorder on to itself.

Non SPD people automatically and unconsciously build memory and knowledge of the connections between words, context and meaning, even for non visual words and non literal senses, like feelings, general sense of time, cues, metaphors, sarcasm. For people with SPD this process is impaired.

Sarcasm, metaphors, abstractions, may all be taken at face value. If you tell someone with SPD "you can spend five minutes to pay your tax on line, but we recommend spending $200 getting your lawyer to do all the things you could do yourself" they may take the sentence literally and go and see their lawyer.

As language styles tend towards the less formal, a new group of people will find themselves less able to function.

Tips for writing for SPD.

• Predictability, this will help them feel secure on your site (blue underline is a link, use standard conventions)
• Simple specific instructions (ask for "family name" not just "name')
• Clear language
• Clearly and explicitly present information and the relationship between information.
• Avoid, or at least label and explain, sarcasm, metaphors, colloquialisms and jokes.
• In XML you can create a "non literal" tag. You could then make a rendering that formats non literal information differently, so that people with SPD can be warned that this phrase is non literal.

And maybe we can encourage HTML to include <non literal> in the next version of XHTML.