In 1989, WordPerfect Corporation released the program's most successful version ever, WordPerfect 5.1 for DOS, which was the first version to include Macintosh style pull-down menus to supplement the traditional F-key combinations, as well as support for tables, a spreadsheet-like feature. The data format used by WordPerfect 5.1 was, for years, the most portable format in the world. All word processors could read (and convert) that format. Many conferences and magazines insisted that you shipped your documents in 5.1 format.