HP 3000 Manuals

HP FORTRAN 77/iX Programmer's Guide

The OPEN Statement Processor 

The FORTRAN 77 OPEN statement gives you more control over file connection
and file characteristics than older versions of FORTRAN. The run-time
library translates the OPEN statement to call the MPE/iX FOPEN system
intrinsic.  The OPEN statement processor implements the options specified
in the OPEN statement by assigning the options to corresponding options
in the FOPEN intrinsic.  The options in the OPEN statement do not
override the characteristics of an existing file; that is, a FILE
equation pertaining to the file takes precedence over the FOPEN
arguments.  Any FOPEN option not specified by FORTRAN 77 is supplied with
the file system defaults.

The options specified in the OPEN statement determine the values of the
FOPTIONS and AOPTIONS arguments to the FOPEN intrinsic.  The default
FILESIZE (number of records) is 4096 and the default NUMEXTENTS (number
of extents allowed) is 32.  Because both values are four times greater
than the MPE/iX default, you do not need a FILE equation with a file of
more than 1023 records.  If the MPE/iX defaults are used, no additional
disc space is allocated for small files.

The name or formal file designator for a file is created by joining the
characters FTN with the two-digit FORTRAN logical unit (LU) number.  For
example, file 8 is FTN08 and file 10 is FTN10.

MPE/iX 5.0 Documentation