VMS Help FORTRAN, Intrinsic Procedures, IDINT  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  IDINT (number)

  A function that returns the largest integer whose absolute value
  does not exceed the absolute value of the argument and has the same
  sign as the argument.

  +------+---------+----------+------------+-------------+
  | Args | Generic | Specific |  Argument  | Result Type |
  +------+---------+----------+------------+-------------+
  |  1   | IDINT   | IIDINT   | REAL*8     | INTEGER*2   |
  |      |         | JIDINT   | REAL*8     | INTEGER*4   |
  +------+---------+----------+------------+-------------+
  The function returns an INTEGER*4 value if the /I4 command
  qualifier is in effect; otherwise it returns an INTEGER*2 value.

  See also the INT intrinsic function.