Applies to capacitors for use in telecommunication and allied electronic circuits, having a rated voltage not exceeding 20 000 V d.c., and of a type specifically suited for resonant circuit application or any other application where low losses and high stability of capacitance are essential and the temperature coefficient is held with constant tolerance on temperature. It does not apply to capacitors for radio frequency currents exceeding 1 A or for a reactive power exceeding 200 var. The classification and ratings are given, and the properties are specified in terms of electrical, climatic and mechanical robustness tests.