With the status word 27 set to 1 fully automatic byte swapping is the default. This works of course only with the EP format as it requires two special control words in the physical header.
To read EP files created in the "OLD" format (with a 6 word
physical header) the user must call EPSETW to set status
word 27 to 0.
The user can force EPIO to read his data as new
format by setting status word 27 to 2, avoiding peculiar side
effects when there are parity errors for example.