/sys$common/syshlp/helplib.hlb FORTRAN, /ASSUME, BYTERECL  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  Controls the unit value for the RECL= keyword in an OPEN or
  INQUIRE statement for unformatted files.

  If BYTERECL is specified, the RECL value is in units of bytes;
  if NOBYTERECL is specified, the RECL value is in units of
  four-byte longwords.  NOBYTERECL is the default and is compatible
  with the default used by Compaq's Fortran products.  NOBYTERECL
  may be used to provide compatibility with non-Compaq platforms.

  To run an application which uses /ASSUME=BYTERECL, OpenVMS VAX V7.0
  or installation of a compatible Run-Time Library is required.  For
  more information, see the Compaq Fortran 77 Release Notes.