This Technical Report lists the gas cylinder valve outlets in use within the countries of ISO member bodies. Its purpose is to prevent further Proliferation. lt is recommended that before allocating a valve outlet to a particular gas Service, member bodies should consult tables 2 to 5 and select, if possible, that outlet associated with the gas which has been adopted by the greatest number of countries. This Technical Repo rt only provides details of the thread type and size. For a more complete description of a particular valve outlet, refer sence should be made to the corresponding national Standard.