Definitions for "Long Description"
a long description is required in an image that is complex such as a graph or chart. In HTML this is done with the longdesc attribute and the D-link which will point to an HTML file. With the Accessibility Wizard, an area is provided for longer descriptions.
an alternate, accessible description of information contained in a complex illustration
A detailed description of the content and any pertinent information the user will need to use the content. This information will be presented on the site in the detailed view of the record, and will usually depict the main terminology, prerequisites, goals, objectives, and / or file-use information for the user.