RECIO_POSITION - position file at start of a record

SUBROUTINE RECIO_POSITION ( FILENUM, RECLEN, RECNUM, STATUS )

   FILENUM = INTEGER (given)
            file number
   RECLEN = INTEGER (given)
            record length in bytes 
   RECNUM = INTEGER (given)
            record number, counting upwards from 1 
   STATUS = INTEGER (given and returned)
            global status