The descriptive text is available for a screen reader device to audibly describe a graph or map so a visually impaired user can understand the graphical information. Corda Technologies has included the descriptive text feature in all members of its Corda Server™ family of data visualization solutions to facilitate inclusion of 508-compliant graphs and maps in all Web content.
www.corda.com/docsource/CenterView2/builder/descriptive_text.htm