Abstract: A method and apparatus for extracting information from an item of data is disclosed. In one embodiment, the invention operates within a packet processing device such as a router. Upon receipt of a data item the data item is analyzed to obtain information regarding the protocol under which the data item was constructed. Different protocol locate relevant processing and routing information at different offsets in a data item's header. As a result of the analysis, the system obtains a protocol key used to identify or obtain offset parameters. In one embodiment the results of the analysis are masked and the protocol key provided to a content addressable memory to identify the offset parameters. Using the offset parameters identified by the protocol key, the system selectively copies portions of the data item to generate a search key. The search key contains information pertinent to processing.