1      Multics provides users with extensive means for communicating with one
 2 another.  For the purpose of discussion here, we will distinguish two kinds of
 3 communication: messages and mail (though elsewhere these terms are often used
 4 interchangably).  Messages and mail are normally read on the computer
 5 terminal, but they can also be printed out on a high-speed printer.
 6 
 7      Because they must be typed on a single "command line," messages are
 8 usually short notes used for rapid communication.  They do not have subject
 9 lines, and they do not list the recipients, even if there is more than one.
10 
11      Mail, on the other hand, is used as a letter would be--for longer
12 communications.  You can send and read mail with either the send_mail and
13 read_mail "commands" or with the Executive Mail facility (the latter is
14 available at most but not all Multics sites).  In either case, the mailbox in
15 which a user's mail is received is the same.  In fact, messages can also be
16 sent to this mailbox if you wish.