Device locking in SVR3.2

[Bob Daniel]

I need to lock a device so that others don't use it while it is locked.  I
have a working way of locking a device but don't know if it follows the
guidlines.  When 'cu' locks a device, it puts a file in /usr/spool/locks as
the file name 'LCK..ttyxx' and it contains the process id of the of process
that has it locked.  This appears to work but is this all there is to it?
I have not found any information in several programmers reference manuals
that I have about device locking.