Can someone show me the syntax for setting up a public mailbox folder for a specific Organisational Unit ... or is it possible at all?

My exchange server has three different organisations. I'm not sure how to set up the public folder mailboxes for these units. I'm not sure if they can be separate, can't be separate or doesn't matter.

Thanks

while creating PF mailbox from EAC, we will get an option to specify OU

is this the one you are referring or restrict permission to user from particular OU ?

What I don't know and which nobody on various forums seems to be able to answer is:

Do I create a public folder mailbox for each organisational unit?
..or do I create one central public folder mailbox for all organisations in the root?

Is it even possible to create one public folder mailbox per organisational unit?

I'm thinking of simply following what this site suggests and hope it works out: http://www.itnotes.eu/?p=3039

(was hoping to understand my options and best practice first)