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

  file-spec-list

  Specifies the source files containing the program units to be
  compiled.  If you do not specify a file type, the compiler uses the
  default file type of FOR, unless /LIBRARY is specified in which
  case the default file type is TLB.

  You can specify more than one input file.  If source file
  specifications are separated by commas (,), the programs are
  compiled separately and an object module is produced for each file.
  If source file specifications are separated by plus signs (+), the
  files are concatenated and compiled as a single input file,
  producing one object file and, if /LIST is specified, one listing
  file.

  For complete information on these command line parameters, see your
  user manual.