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]