This part of IEC 62317 specifies the dimensions that are of importance for mechanical interchangeability for ETD-cores made of ferrite, the essential dimensions of coil formers to be used with them, and the effective parameter values to be used in calculations involving them.

The use of “derived” standards which give more detailed specifications of component parts while still permitting compliance with this standard is discussed in Annex A, which also contains an example of a derived standard for coil formers.