A method using a digital data processing system and a query composed of entries locates entries in a stored multiple layer data base. The entries have one or more event types, and the entries of the data base include entries which have either an exact or an inexact match with entries of the query. The query and a first one of the data base layers are processed to form packages having an assigned order. The packages contain representations of event types in a second layer of the data base (entries in the first layer) and representations of the degree of match between the entry in the first layer and an entry of the query. Representations of the packages and representations of entries in a second one of the data base layers are processed to form a degree of match therebetween and to form representations of entries on the second one of the data base layers. For each of individual ones of the entries in the packages, a representation of a further degree of match for such entry is determined and formed. Representations of the degree of match represented in each of plural ones of the packages are processed to form the representation of the further degree of match for each entry as a function of the representations of the degree of match in the packages. As a result the representations of the further degree of match represent the degree of match of the query to both the first and second layers of the data base.