Tuesday, November 11, 2008

Frames

Why is this provision necessary?

Frames provide a means of visually dividing the computer screen into distinct areas that can be separately rewritten. Unfortunately, frames can also present difficulties for users with disabilities when those frames are not easily identifiable to assistive technology. For instance, a popular use of frames is to create "navigational bars" in a fixed position on the screen and have the content of the web site retrievable by activating one of those navigational buttons. The new content is displayed another area of the screen. Because the navigational bar doesn't change, it provides a stable "frame-of-reference" for users and makes navigation much easier. However, users with disabilities may become lost if the differences between the two frames are not clearly established.
What is the best method for identifying frames?

The most obvious way to accomplish this requirement is to include text within the body of each frame that clearly identifies the frame. For instance, in the case of the navigation bar, a web developer should consider putting words such as "Navigational Links" at the beginning of the contents of the frame to let all users know that the frame depicts navigational links. Providing titles like this at the top of the contents of each frame will satisfy these requirements. An additional measure that should be considered by agencies is to include meaningful text in the frame tag's "title" attribute. Although not currently supported by major manufacturers of assistive technology, the "title" attribute is part of the HTML 4.0 specification and was intended to let web developers include a description of the frame as a quote-enclosed string. Demonstrating the use of the "title" attribute requires a basic understanding of how frames are constructed. When frames are used in a web page, the first page that is loaded must include a frameset tag that encloses the basic layout of the frames on the page. Within the frameset tag, frame tags specify the name, initial contents, and appearance of each separate frame. Thus, the following example uses the "title" attribute to label one frame "Navigational Links Frame" and the second frame "Contents Frame."

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