EVS-EN IEC 63093-8:2018

This part of IEC 63093 specifies the dimensions that are of importance for mechanical interchangeability for a preferred range of E-cores made of ferrite, the essential dimensions of coil formers to be used with them as well the effective parameter values to be used in calculations involving them, and gives guidelines on allowable limits of surface irregularities applicable to E-cores.
This document is a specification useful in the negotiations between ferrite core manufacturers and customers about surface irregularities.
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.