This expression says that an advertisement covers a notification if and only if it covers each individual attribute in the notification. Note that this is the dual of subscriptions, which define the minimal set of attributes that a notifi- cation must contain. In contrast to subscriptions, when a filter is used as an advertisement, multiple constraints for the same attribute are interpreted as a disjunction rather than as a conjunction; only one of the constraints need be satisfied. Table III shows some examples of the relation ÁN A . The second exam- ple is not a match because the attribute date of the notification is not defined in the.
