Recommendation ITU-T Z.165 provides the specification of the runtime interface for TTCN-3 test system implementations. The TTCN-3 runtime interface provides a standardized adaptation for timing and communication of a test system to a particular processing platform and the system under test@ respectively. This Recommendation defines the interface as a set of operations independent of target language. The interface is defined to be compatible with the TTCN-3 standard. The present document uses the CORBA Interface Definition Language (IDL) to specify the TRI completely. Clauses 6@ 7 and 8 of [ETSI ES 201 873-5 V4.5.1] present language mappings for this abstract specification to the target languages Java@ ANSI C@ and C++. A summary of the IDL-based interface specification is provided in Appendix A of [ETSI ES 201 873-5 V4.5.1].