The format of a log trace is hh:mm:ss.fff log_level emiter message where :
|NONE||6||This level can't be used to send a message. It exists only for filtering purpose.|
The logging system is defined around a chain of filtering. A component which want to send a message will actually forward it his parent in the chain which will have responsibility to determine if it will forward it through. A message is logged only if it reach the core which is the only one allowed to print a log message.
A message is forwarded if the local level of logging (LOCAL_LEVEL) is lower or equals to the level of the logged messages (MESSAGE_LEVEL).
LOCAL_LEVEL <= MESSAGE_LEVEL
For example for node1 and node0 with respectively logging levels of INFO and ERROR, if comp0 send a message with level INFO it will be forwarded by node1 but will be discarded by node0 (and consequently not printed).
But if chan0 send a message of level ERROR, it will be forwarded by both node1 and node0 and then printed by the core.