What Is Being Named?

Which entity is being named? Consider telephones and telephone numbers (analogous to message handling in a message processing system). If, as before, we consider a phone number to be the name of a telephone, then:

• a telephone may have several names (several numbers ringing the same phone);

• a given number could ring several phones: the several extensions in your home, or the phones of a manager and his secretary;

• phones can change names (numbers): the phone company replaces a defective telephone, or the phone company assigns new numbers, or you transfer your number when you move.