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 programssimilar 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]