When a categoriser isn't sufficient for your needs, you
          can write an Lire::DlfAnalyser which
          gets complete control on the analysis process. The main
          difference with at categoriser is that the
          dst_schema method will contain
          refer to a derived schema instead of an extended schema.
        
The core of the analyser is done in the
          analyse method that takes 
          a reference to the store onto which data will be analysed
          and to a Lire::DlfAnalyserProcess
          callback object which should be use to write new DLF records
          and report errors. The method also receives the plugin
          configuration data. The analyser should create a
          Lire::DlfQuery to select the records
          necessary for its analysis.
        
The doc/examples in the source
          distribution contains the a boiler plate for witing an Analyser.