time T /ti:m T/ n. 1. An unspecified but usually well-understood time,
   often used in conjunction with a later time T+1. "We'll meet on campus
   at time T or at Louie's at time T+1" means, in the context of going out
   for dinner: "We can meet on campus and go to Louie's, or we can meet at
   Louie's itself a bit later." (Louie's was a Chinese restaurant in Palo
   Alto that was a favorite with hackers.) Had the number 30 been used
   instead of the number 1, it would have implied that the travel time from
   campus to Louie's is 30 minutes; whatever time T is (and that hasn't
   been decided on yet), you can meet half an hour later at Louie's than
   you could on campus and end up eating at the same time. See also {since
   time T equals minus infinity}.


Source: The Jargon File