SOS

SOS n.,obs.  /S-O-S/ 1. 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).  2. /sos/ vt. To decrease; inverse of {AOS}, from
   the PDP-10 instruction set.