4.0 was released in 1984. WordPerfect 4.2, released in 1986, introduced automatic paragraph numbering, which was important to law offices, and automatic numbering and placement of footnotes and endnotes that were important both to law offices and academics. It became the first program to overtake the original market leader WordStar in a major application category on the DOS platform. By 1987, Compute! magazine described WordPerfect as "a standard in the MS-DOS world" and "a powerhouse program that includes almost everything". In November 1989, WordPerfect Corporation released the program's most successful version, WordPerfect 5.1 for DOS, which was the first version to include pull-down menus to supplement the traditional function key combinations, support for tables, a spreadsheet-like feature, and full support for typesetting options, such as italic, redline, and strike-through. This version also included "print preview", a graphical representation of the final printed output that became the foundation for WordPerfect 6.0's graphic screen editing. WordPerfect 5.1+ for DOS was introduced to allow older DOS-based PCs to utilize the new WordPerfect 6 file format. This version could read and write WordPerfect 6 files, included several third-party screen and printing applications (previously sold separately), and provided several minor improvements. WordPerfect 6.0 for DOS, released in 1993, could switch between its traditional text-based display mode and a graphical display mode that showed the document as it would print out known as WYSIWYG (what you see is what you get). The previous text-based versions used different colors, or text color inversions to indicate various markups, and a graphic mode only for an uneditable print preview that used generic fonts rather than the actual fonts that appeared on the printed page. By the time WordPerfect 6.0 was released, the company had grown "to command more than 60 percent of the word processing software market." Key characteristics WordPerfect's distinguishing features include: extensive use of key combinations, especially on the MS-DOS platform, enabling quick access to features, once the meaning of the key combinations (like Ctrl–Shift–F6) had been memorized; its "streaming code" file format; its Reveal Codes feature; and its numbering of lines as the legal profession requires its macro/scripting capability, now provided through PerfectScript. The ease of use of tools, like Mail Merge (combine form documents with data from any data source), "Print as booklet", and tables (with spreadsheet capabilities and the possibility to generate graphs) are also notable. The WordPerfect document format allows continuous extending of