scope:

This standard covers iron core inductors for use in electronic equipment in which long life, reliability, and continuity of operation are essential and which are employed for frequency discrimination elements or for filters other than power supply application. It also covers those characteristics of transformers which are otherwise covered by the RETMA Audio Transformer Specification, but wherein one or more windings are employed as tuned elements.

It is not intended that the frequency be limited to the region of audio frequencies.