 Margorie Orr supervised the OS simulation program development and maintenance.Some of the programmers who wrote parts of the OS simulation package, or maintained it were Margorie Orr, Timothy Greiser, Daniel Levbre, John Coldwell Lotz, and Paul Cheffers.Michael Krugman wrote some of the early main utilities such as IFMSG, the JCL language for VPS, and also MAIL, the early email program.