/[NO]F77

  Controls whether the compiler uses FORTRAN-77 interpretation rules
  for those statements that have a meaning incompatible with
  FORTRAN-66.  See the HP Fortran for OpenVMS User Manual for a
  discussion of these incompatibilities.

  The default is /F77.  If you specify /NOF77, the compiler selects
  FORTRAN-66 interpretations in cases of incompatibility.

  If you omit /NOF77, DO loops whose lower range exceeds the upper
  range are not executed.

  You can also specify this qualifier using the OPTIONS statement.