If the aggregate is configured to inherit attributes from its aggregated routes (that is, if the asSet, summaryAsSet, asPrepend or summaryAsPrepend option is set), this field can be used to specify the subset of aggregated routes from which the aggregate will inhert its attributes. It specifies the index of a Route Map, the match clauses of which define this subset. This is equivalent to the 'advertise-map' feature available in other BGP implementations.