HTML 5 and the Summary Attribute
http://www.456bereastreet.com/archive/200909/html_5_and_the_summary_attribute/

Johansson, Roger
456 Berea Street
2009

Abstract:

As I wrote in Help screen reader users by giving data tables a summary, the summary attribute on the table element can be used to provide information that helps non-sighted users understand data tables. The current draft of HTML 5 requires that validators display a warning if they encounter a summary attribute, since it is now an 'obsolete but conforming feature.'