VMS Help FORTRAN, Logical Names, FOR$CONVERTnnn  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  If defined during execution, this logical name specifies a default
  data conversion type for unit "nnn".  The translation of the
  logical name must be a valid keyword for the /CONVERT= qualifier.
  For example:

      $ DEFINE FOR$CONVERT002 LITTLE_ENDIAN

  This command makes LITTLE_ENDIAN the default convert type for unit
  2.  A defined logical name for a unit overrides the /CONVERT
  compile command or OPTIONS statement qualifier and an explicit
  CONVERT= keyword on an OPEN statement.  For more information, see
  the /CONVERT qualifier.