http://www.rfc-editor.org/rfc/rfc7799.txt
RFC 7799: Active and Passive Metrics and Methods (with Hybrid Types In-Between), A. Morton2016-05-01T23:00:00-00:00This memo provides clear definitions for Active and Passive performance assessment. The construction of Metrics and Methods can be described as either "Active" or "Passive". Some methods may use a subset of both Active and Passive attributes, and we refer to these as "Hybrid Methods". This memo also describes multiple dimensions to help evaluate new methods as they emerge.