How does AIX lock mail?

[Greg Fisher]

I am trying to set up emacs RMAIL on an IBM RS/6000.  I need to know
which locking scheme it useds.  The emacs installation help says there
are two ways, but does not say how to tell which one to used.  

The m-ibmrs6000.h file has commented out MAIL_USE_FLOCK, but the
/usr/ucb/mail program on my system does not have write permission on
/usr/spool/mail.  That suggests that it may actually be using flock.

Thanks,
	Greg Fisher
	fisher at iscp.bellcore.com