The Jargon File (version 4.4.7, 29 Dec 2003):

three-finger salute
 n.

    Syn. Vulcan nerve pinch.


The Free On-line Dictionary of Computing (30 December 2018):

Vulcan nerve pinch
three-finger salute

    (Or "three-finger salute", Vulcan death grip; from
   the old "Star Trek" TV series via Commodore Amiga
   hackers) The keyboard combination that forces a soft boot
   or jump to ROM monitor (on machines that support such a
   feature).

   On an Amiga this is done with Ctrl/Right Amiga/Left Amiga; on
   IBM PCs and many microcomputers it is Ctrl/Alt/Del; on
   Suns, L1-A; on some Macintoshes, it is -!  Silicon Graphics users are obviously the most
   dextrous however, as these machines use the five-finger
   combination: Left Shift/Left Ctrl/Left Alt/Keypad Divide/F12.

   Compare quadruple bucky.

   [Jargon File]

   (2000-04-04)