Abstract: A memory system and search method are provided for searching a multi-field longest prefix match (LPM) in a search term. The method provides a first LPM rule memory, where an LPM rule includes explicitly defined bit values in at least the n most significant bit (MSB) positions in a field of digital information, where n is an integer greater than or equal to 0. The method accepts a search term and compares at least a first field in the search term to subset rules structured in a sorted search tree for a first field organized as a LPM rule in the first LPM memory. When an explicit match is not found to the subset rules, the first field in the search term is compared to superset rules for the first field in the first LPM memory. As a final step, the method performs an instruction associated with a matching rule.