WordStar is the first mass-market word processing program with a WYSIWYG (what-you-see-is-what-you-get) interface. Other pioneering innovations included cut-and-paste, and mail merge commands. The program relied on a unique set of keyboard commands that were memorized by millions of users and continued to affect keyboard shortcut layouts well into the 1980s. (The lingering influence of this keyboard command set is attested by the continued availability of a Microsoft Word add-on program that emulates keyboard commands.) Released in 1978 for the CP/M operating system, was made available in an MS-DOS version in 1982; however, the program met stiff competition from WordPerfect, which quickly dominated the market. A 16-bit version was made available for Microsoft Windows 3.0 in 1999.