File locking of mboxrd-format mbox file

[Frank Watt]

I'm looking at the getmail documentation at

http://pyropus.ca/software/getmail/configuration.html#conf-retriever

In the Mboxrd destination description it states in red letters:

You must ensure that all other programs accessing any the mbox file 
expect mboxrd-format mbox files and the same type of file locking that 
you configure getmail to use; failure to do so can cause mbox corruption...

My question is: how do I know what type of file locking that has been in 
use all these years of using fetchmail?

BTW, Is "mbox" the standard abbreviation of Mboxrd or is it something 
else?  I understood that fetchmail has been using mbox format, but I 
could have been misled.

TIA

Frank