This tag was from the original HTML 3.0 Math working draft. The browser to implement these tags was UdiWWW that is no longer supported. Because UdiWWW supported these tags, and it was released to the public for use, they are included here. Another working draft is currently being circulated at W³C "Math Markup Language" working draft dated 10-Jul-97. These tags will not be included until they are supported by a publicly available browser or achieves the status of a recommendation.