Indicates the level of assurance for delivery of an Application Message http://docs.oasis-open.org/mqtt/mqtt/v3.1.1/os/mqtt-v3.1.1-os.html#_Table_3.11_-
At most once delivery
At least once delivery
Exactly once delivery
Reserved – must not be used
Failure - used in SubAck packet only
See Implementation
Indicates the level of assurance for delivery of an Application Message http://docs.oasis-open.org/mqtt/mqtt/v3.1.1/os/mqtt-v3.1.1-os.html#_Table_3.11_-