VMS Help PASCAL, Predeclared Routines, Transfer, INT64  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  The INT64  function  converts  the  parameter  and  returns  its
  INTEGER64 equivalent.

  Syntax:

         INT64(x)

  Overflow can occur  and  is  detected  at  runtime  if  overflow
  checking is enabled and the value of 'x' is outside the range of
  INTEGER64.