README.SCO-TTY-NAMES

Under SCO prior to 32v5 or Open Server 5, SCO observes the
convention of using the last character of the tty file name
(always an alpha character) to indicate whether a tty file name
refers to the _direct_ (ignoring control signals) or to the
_modem_ (observing control signals) access methods for the same
physical port.

A file name with an _upper case_ character refers to the modem
access method.  A file name with a _lower case_ character refers
to the direct access method.

/dev/tty1a refers the same physical port as /dev/tty1A, but with
differing access methods.

The choice of tty file names is established (by SCO) in pre-32v5
UNIX by use of the kernel configuration file
/etc/conf/node.d/sio.  Some sample contents:

sio     tty1A   c       128
sio     tty1a   c       0

Note the choice of "tty1A" and "tty1a" in the file is completely
`arbitrary' from the point of view of the kernel building
facility.  The convention is set by the system architect who
chose to assert the name relationship we have enjoyed, lo, these
many years.  A simple examination shows this choice to be FAR
superior to such decisions as "acu0", "ttyd0" and "ttya" found on
certain unnamed "systems." SCO follows their convention for
pre-32v5 all the way back to the very advent of Xenix (and SCO
UNIX of course).

A problem arises with third party vendors who do not use
the convention (maybe they have 900 port boards).

The result is that *NO* convention exists for lock names of this
type (like the foreign system's acu0, ttyd0, ttya case).

The solution for this is that in 32v5 and later, SCO now mandates
that lock file names be now constructed by converting *ALL*
filename characters to lower case, not just the last.  This does
not cover the degenerate case of /dev/ttyHotTubDcdParadise01 and
/dev/ttyHotTubDownAndDirty01, but just think of it as evolution
in action :).

This means:
	/dev/ttyA08	locks to 	LCK..ttya08
	/dev/ttya08	locks to 	LCK..ttya08