Accessible web design		Content & navigation • HTML • Interactive & other media • WebCT accessibility issues • Validation

Validation

Validation is a checking process that ensures the validity of HTML code and can also check for possible accessibility problems. While it is useful to submit pages to a validation process, it is far from foolproof. It is usual for pages to generate what appears to be a list of 'errors', when the page is in fact conforming to accessibility guidelines. The reason for this is that validity checkers cannot determine:

• how appropriate an 'alt' tag is - it will ask you to check manually
• when an image requires a 'longdesc' tag (link to page with long description) - it will ask you to check manually
• how a table is being used - it will assume that a table used for layout contains data and requires 'header' cells to be identified
• whether colour is being appropriately used
• whether styles are being appropriately used

When checking this page for errors, the Dreamweaver accessibility check advised that some links were to audio files and required a transcript - in fact the links are to URLs with a '.au' extension - an Australian domain not recognised by the USA-centric software!

It is commendable that software developers are now ensuring that the latest versions of their software (eg Macromedia Dreamweaver, Adobe Acrobat) enable users to produce documents that are as accessible as possible, and include a function to check for accessibility. It does not necessarily follow that all accessibility requirements are yet supported by the software interface. For example, the Dreamweaver accessibility check will advise you to provide 'longdesc' tags, while not supporting that in it's interface. This issue is in continual development, and it is advisable to check software developer websites for any support or upgrades that may be available:

• Macromedia product accessibility info: http://www.macromedia.com/macromedia/accessibility/
• Adobe Accessibility info: http://access.adobe.com/information.html

Validation services are also available on the internet:

• Send pages for online checking, or download a checking utility at: http://www.cast.org/bobby.
• The W3C consortium provides validation services for HTML at: http://validator.w3.org and for CSS at: http://jigsaw.w3.org/css-validator
• A-Prompt toolkit - free software to verify the accessibility of your web pages: http://www.aprompt.ca/

The bottom line is, however, that no check is as useful as one performed by a developer who is aware of accessibility guidelines, and is thorough in applying them.

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