Content developers need to know about objects, equivalence, graceful depreciation and the techniques for producing these. It may be useful to think of objects, such as a movie clip, as best constructed of all the deprecated forms that will accompany it - linked together using SMIL. in other words, if you are developing an object to go in a resource, think ahead of all the other forms that object may need to take, and make them at the same time.This way, all users get to enjoy the value of the development and some are not left either with nothing, or with only a skeletal version.
'Equivalence' in the accessibility context means that a user who, for one reason or another, avoids one presentation of a resource, can choose an alternative resource to gain an 'equivalent' experience. It is an open question what is equivalent to the range of resources and activities being developed for what is seen as a museum's target audience.
The IMS Accessibility Guidelines White Paper (http://www.imsproject.org/) says:
"When considering the accessibility of applications and software for learning, education, and training, it is important to understand the differences between two types of access: equivalent and alternative.
Equivalent Access provides the learner with the same learning activity but it is mediated in a different modality. Providing a course textbook in Braille format, on audio tape, or in digital format are examples of equivalent accessibility. Alternative Access provides the learner with a different learning activity but one that is designed to achieve the same learning objectives. An example of alternative accessibility might be having a mobility-impaired student conduct science experiments in a virtual laboratory, where the same levels of dexterity, strength, and physical access are not required as in a physical laboratory."
This is the notion that an object can be transformed into alternative formats or modalities for the benefit of users with special needs or preferences.
Last updated: 8 March 2002