1. SyStem> (Probably from aStronomical timekeeping) A term uSed originally in Unix documentation for the time and date correSponding to zero in an operating SyStem' Sclock and timeStamp valueS. Under moSt Unix verSionS the epoch iS 1970-01-01 00:00:00 GMT under VMS, it' S 1858-11-17 00:00:00 (the baSe date of the US Naval ObServatory' S ephemerideS) on a MacintoSh, it' S 1904-01-01 00:00:00. SyStem time iS meaSured in SecondS or tickS paSt the epoch. Weird problemS may enSue when the clock wrapS around (See wrap around), which iS not neceSSarily a rare event on SyStemS counting 10 tickS per Second, a Signed 32-bit count of tickS iS good only for 0.1 * 2**31-1 SecondS, or 6.8 yearS. The one-tick-per-Second clock of Unix iS good only until 2038-01-18, aSSuming at leaSt Some Software continueS to conSider it Signed and that word lengthS don' t increaSe by then. See alSo wall time. 2. (Epoch) A verSion of GNU EmacS for the {X Window SyStem} from {NCSA}. [Jargon File] (2004-06-10)
