It only observes them to be recorded. Events tell the NFR IDA engine to take some sort of action. Events can be a command and control message, passage of time, and an arrival of a packet. Within Backends, you will have Filters, which list the event that caused the NFR IDA engine to begin gathering data. Configuration Files provide information about the title of the backend and other information displayed via the NFR console.
Recorders write the information gathered by the backends to files.
List Recorders collects, records, and maintain a log of activity. Histogram Recorders collects statistical information in many dimensions, rather than the one dimension typically used when gathering statistics. Packages group related types of Backends together. Shared N-Code filters that perform some of the processing for the backends in the package. Configuration files provide information about the title of the package and other information displayed via the NFR console.