object UserDB
    components: UserRecord*;
    operations: AddUser, FindUser, ChangeUser, DeleteUser;
    description: (*
        UserDB is the repository of registered user information.
    *);
end UserDB;

object UserRecord
    components: name:Name and id:Id and email:EmailAddress and
        phone:PhoneNumber;
    description: (*
        A UserRecord is the information stored about a registered user of the
        Calendar Tool.  The Name component is the user's real-world name.  The
        Id is the unique identifier by which the user is known to the Calendar
        Tool.  The EmailAddress is the electronic mail address used by the
        Calendar Tool to contact the user when necessary.  The PhoneNumber is
        for information purposes; it is not used by the Calendar Tool for
        contacting the user.
    *);
end User;

object Name = string;
object Id = string;
object EmailAddress = string;
object PhoneNumber = area:Area and num:Number;
object Area = integer;
object Number = integer;