"This ETS contains the technical characteristics required for end-to-end interworking over the Public Switched Telephone Network (PSTN). Clauses of this ETS also contain Category II specifications define for certain features which may be provided by some modems@ but the requirements in these parts are only applicable when invoked by a modem specific ETS. The term ""modem"" in the context of this ETS includes all physical implementation practices for voice band modems which are conductively connected to the PSTN. NOTE: This implies that certain types of modems@ e.g. acoustically coupled arid cordless modems@ are outside the scope of this ETS. This ETS also contains descriptions of the tests to be performed in order to confirm compliance with the functional requirements contained herein. A general description of the test conditions and test requirements for clause 4 is given in annex A (informative) and for clause 5 in annex B (normative). Annex C (normative) descnbes the testing facilities which a testing laboratory may need to provide. Annex D (normative) indicates additional equipment@ or software@ that applicants may need to provide in order that testing to Category II can be achieved."