He says that accessibility means designing computing environments that can be used by anyone. At ATA, we define disability not as a flaw in an individual, but as a design defect in the environment. When there are curb cuts and door openers, the use of a wheelchair ceases to be a disability. If I can speak to my computer, a neuromuscular disorder becomes much less of a disability in a work environment. They needed to understand exactly what was wrong and what was needed to correct it.
Software is accessible if a blind person can use all major features of it with a screen reader.
Thatcher divided the problem into three parts. A user has to be able to get there, know where he is, and know what he can do in that area at all times. An understanding of how people with disabilities work differently with computer technology is fundamental. People with visual impairments don't use a mouse to access toolbars, radio buttons, or push buttons. Accessible software must translate mouse actions into keyboard equivalents.