Attribute	Attribute Meaning
total_count	Total cumulative count the concerned DataReader discovered a “match” with a DataWriter. That is, it found a DataWriter for the same Topic with a requested QoS that is compatible with that offered by the DataReader.
total_count_change	The change in total_count since the last time the listener was called or the status was read.
last_subscription_handle	Handle to the last DataWriter that matched the DataReader causing the status to change.
current_count	The number of DataWriters currently matched to the concerned DataReader.
current_count_change	The change in current_count since the last time the listener was called or the status was read.

The DataReader has found a DataWriter that matches the Topic and has compatible QoS or ceased to be matched with a DataWriter.