Report Program Generator. Programming language widely used on the eserver iSeries 400 and its predecessors: AS/400 and System/3x. Coding is column-dependent fill-in-the-blanks forms. As its name implies, best used for report generation, and very strong sort/merge facilities, where it can be used completely non-procedurally. IBM created RPG in 1965. RPG/370 was the mainframe SAA CPI version announced February 1991 and withdrawn August 1993. It ran on z/OS and z/VM. For VSE/ESA, there is DOS/VS RPG II, still available, but it has been more than two decades since the last release. OS/VS RPG II, for z/OS, is even older. Hopefully, someone checked them both for Y2K compatibility. RPG’s major popularity on the mainframe came at the low end, as it was the only programming language that ran very well on the System/ 360 Model 20. For the iSeries 400, where virtually all of the RPG use occurs today, WebSphere Development Studio for iSeries includes ILE RPG (RPG IV), VisualAge RPG and CODE/400, the tools of choice for RPG programmers. They run on OS/400 and Windows.