Supporting Standards

• tabindex only defined for a and form control elements in HTML 4.01
• role is inly defined in xhtml2, but soon will be in xhtml 1.2
• Properties and states are not part of any HTML and xhtml standards, problem for HTML documents
• Microsoft Internet Explorer does not support "application/xhtml+xml" MIME type
• Microsoft Internet Explorer does not support use of properties and states as CSS selectors