asterisk users - Jan 2010 - Adminpin for conference room

Hello,

Can someone please explain me how the adminpin for conference rooms is used?

In the following dialplan
exten => 1122,1,MeetMe(${conf-room-no})

If users join this conference by dialing adminpin or pin will it make
any difference to the user?

Does dialling the adminpin give the user any kind of control of the
conference room?

Thanks