This Recommendation specifies requirements and gives guidance concerning the realization of Means of Testing (MOT) for Implementation under Test (IUTs), in conformance with a reference Abstract Test Suite (ATS) specified in compliance with Recommendation X.291. Test realization involves a protocol, multiple protocols or profile. The text was developed jointly with ISO/IEC JTC 1 and the main intent of this revision is to reflect the changes as a result of the work on Protocol Profile Testing Methodology (PPTM) and on Multi-Party Testing Methodology (MPyTM).