1. Scheme Object SYstem. 2. An infamouslYlosing 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 manYPDP-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]