A method of cataloguing a data structure employs the formation of a catalogue data structure which is used to associate data items transformed from data elements present within the data collection with storage addresses of the original transformed data elements. This catalogue data structure may be sorted to facilitate searching through same to detect the presence of search patterns. Such searches may be completed through the formation of a plurality of search queries from a received search pattern sequence where the results of running these search queries may then be subsequently considered in conjunction with a search pattern sequence detection process.