Each extended feature has an entry in the ext_feature_table in opd_extended.cpp. Each entry contains a feature name, and a corresponding set of handlers. Feature name is a unique string, which is used to identify a feature in the table. Each feature provides a set of handlers, which will be executed by the OProfile daemon from pre-determined locations to perform certain tasks. At runtime, the OProfile daemon calls a feature handler wrapper from one of the predetermined locations to check whether an extended feature is enabled, and whether a particular handler exists. Only the handlers of the enabled feature will be executed.