Recommendation ITU-T Z.161 defines the core language of TTCN-3. TTCN-3 can be used for the specification of all types of reactive system tests over a variety of communication ports. Typical areas of application are protocol testing (including mobile and Internet protocols)@ service testing (including supplementary services)@ module testing@ testing of CORBA based platforms@ APIs@ etc. TTCN-3 is not restricted to conformance testing and can be used for many other kinds of testing including interoperability@ robustness@ regression@ system and integration testing. The specification of test suites for physical layer protocols is outside the scope of this Recommendation. TTCN-3 is intended to be used for the specification of test suites which are independent of test methods@ layers and protocols. Various presentation formats are defined for TTCN-3 such as a tabular presentation format and a graphical presentation format. The specification of these formats is outside the scope of this Recommendation. While the design of TTCN-3 has taken the eventual implementation of TTCN-3 translators and compilers into consideration the means of realization of Executable Test Suites (ETS) from Abstract Test Suites (ATS) is outside the scope of this Recommendation.