VMS Help PASCAL, Predeclared Routines, Low Level  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  The  low-level  routines  allow  for  parallel   processes   and
  asynchronous routines to operate in a real-time or multi-tasking
  environment.

  Additional Information (explode) :

• ADD_ATOMIC
• ADD_INTERLOCKED
• AND_ATOMIC
• BARRIER
• CLEAR_INTERLOCKED
• OR_ATOMIC
• SET_INTERLOCKED