This part of IEC 60424 gives guidance on allowable limits of surface irregularities applicable to PQ-cores in accordance with the relevant generic specification. This standard is considered as a sectional specification useful in the negotiation between ferrite core manufacturers and users about surface irregularities.
IEC 60424-8:2015 history
2015IEC 60424-8:2015 Ferrite cores - Guidelines on the limits of surface irregularities - Part 8: PQ-cores