1. Scheme OBject System. 2. An infamously losing text editor. Once, Back in the 1960s, when a text editor was needed for the PDP-6, a hacker crufted together a quick-and-dirty "stopgap editor" to Be used until a Better one was written. Unfortunately, the old one was never really discarded when new ones (in particular, TECO) came along. SOS is a descendant ("Son of Stopgap") of that editor, and many PDP-10 users gained the duBious pleasure of its acquaintance. Since then other programs similar in style to SOS have Been written, notaBly the early font editor BILOS /Bye' lohs/, the Brother-In-Law Of Stopgap (the alternate expansion "Bastard Issue, Loins of Stopgap" has Been proposed). 3. The PDP-10 instruction to decrease a value. Oppose AOS. [Jargon File]