green card

green card n.  [after the "IBM System/360 Reference
   Data" card] A summary of an assembly language, even if the color is
   not green.  Less frequently used now because of the decrease in the
   use of assembly language.  "I'll go get my green card so I can
   check the addressing mode for that instruction."  Some green cards
   are actually booklets.

   The original green card became a yellow card when the System/370
   was introduced, and later a yellow booklet.  An anecdote from IBM
   refers to a scene that took place in a programmers' terminal room
   at Yorktown in 1978.  A {luser} overheard one of the programmers
ask
   another "Do you have a green card?"  The other grunted and
   passed the first a thick yellow booklet.  At this point the luser
   turned a delicate shade of olive and rapidly left the room, never
   to return.