The following are considered:
| text | tables | forms
sounds | images | animated or moving images - without sound | videos
interactive multimedia | course management software
In general, the following problems should be accommodated on a primary web page, and all forms of depreciation should be offered as equivalent content on the same primary page. Text alternative pages or sites are as inhospitable as back entrances for the disabled and should be avoided.
All interactivity with web material should be possible using keyboard commands as many users have problems with use of a mouse.
Navigation is always a problem on websites: the structure of the site should be clear; sitemaps should be provided; links should have text labels and lead where they indicate, to support user predictability; 'back' and next buttons should be used carefully; frames should not be used as navigation bars;
Users can have problems with the following:
Users will have, or choose to use, windows of all sizes. All content should be 'elastic' and able to grow or shrink according to user needs. Windows should not proliferate (with pop-outs) and frames should not be used.
This should be
These should be used only for content that is tabular, two-dimensional. Using tables for layout may be unavoidable in the short term but in such a case, effective linearisation is essential. Tables should have 'labels' that explain their structure and content to users.
These need to be constructed so that input follows labels in a logical way and what is required to be input is clearly identified.
These should be easily understood, with link text identifying linked object (not 'Click here' but 'maps'). Navigation bars should not be in frames but can be located by styles that depreciate appropriately.
Many users do not have, or choose not to have, access to sound. Content and its use should not depend upon sound without text and/or image alternatives. Not all deaf people can read English, which is a second language for them. Many deaf people use sign languages that are effectively different languages into which content may need to be translated. English, for instance, cannot be 'signed' - and deaf Australians communicate in a different sign language from deaf US people. Text that is signed is translated into Auslan.
Many people cannot access images: they may be using equipment that does not cater for images, they may have sight or colour disabilities, or they may be blind. Equivalent content should always be provided when images are used for other than decoration. Decorative images should be dispensible and styled as such. All relevant images should be labelled and those with essential content should have comprehensive text equivalents.
Images should resize and reposition appropriately when window sizes change. Images stored as 'scalable vector graphics' have small file-sizes and resize witout deterioration. Only some browsers support this standard in 2001.
Image descriptions, as well as titles, can be used to provide equivalent content for users. Image equivalents should provide users with experiences equivalent to viewing the images but may not be descriptions of the images. For instance, a diagram explaining a scientific process may be better replaced by a text explanation that uses a verbal metaphor.
Moving images have all the problems of still images with the additional factor of change over time. Equivalent content may need to be related to each section of the animated image or can be used to replace the whole.
Videos that include images and sounds can be inaccessible in different ways for different groups of users:
Where interactivity depends upon mouse location, many users are unable to navigate the material and they are unable to interact unless there are keyboard alternatives. The timing of interactivity may need to be adjusted to suit the speed of adaptive technologies, eg a Braille reader may need more time than a sighted reader because of delays in the Braille representation.
Course management software that is used to provide web resources to students may interfere in the accessibility of the original material. Course management packages should be evaluated for accessibility and used only in ways that promote the continuing accessibility of otherwise accessible resources.
Last updated: 8 March 2002