[Exim] mail locking

Hi!

My xemacs need to know what style of locking is used on my
system. Here is options:

--mail-locking=TYPE (*) Specify the locking to be used by movemail to prevent
                        concurrent updates of mail spool files. Valid types
                        are `lockf', `flock', `dot', `locking' or `mmdf'.

Which of them does used in exim?

--
Alexey Promokhov <ayp(at)ayp.msk.ru>, 2:5020/2388.1513@fidonet