A structure storing a matching status.
Total cumulative count the concerned reader discovered a match with a writer.
It found a writer for the same topic with a requested QoS that is compatible with that offered by the reader
The change in total_count since the last time the listener was called or the status was read.
The number of writers currently matched to the concerned reader.
The change in current_count since the last time the listener was called or the status was read.