Description

   By default, TPU$FILEIO creates variable-length files with
   carriage-return record attributes (FAB$B_RFM = VAR, FAB$B_RAT
   = CR). If you pass to it the TPU$K_RECORD_ATTR or TPU$K_RECORD_
   FORM item, that item is used instead.

   The following combinations of formats and attributes are
   acceptable:

   Format           Attributes

   STM,STMLF,STMCR  0,BLK,CR,BLK+CR
   VAR              0,BLK,FTN,CR,BLK+FTN,BLK+CR

   All other combinations are converted to VAR format with CR
   attributes.

   This routine always puts values greater than 511 in the first
   longword of the stream data structure. Because a user-written
   file I/O routine is restricted to the values 0 through 511, you
   can easily distinguish the file control blocks (FCB) this routine
   fills in from the ones you created.

                                  NOTE

      TPU uses TPU$FILEIO by default when you use the
      simplified callable interface. When you use the full
      callable interface, you must explicitly invoke TPU$FILEIO
      or provide your own file I/O routine.