This part of IEC 60641 contains definitions related to a classification of, and the general requirements to be fulfilled by, pressboard and presspaper for electrical purposes. The main changes with respect to the previous edition are: the kind of surface finish shall no longer be specified in the standard, fixed nominal thicknesses have been replaced by preferred thicknesses, types B.6 and P.6 have been replaced, but the designations have been kept and types B.7 and P.7 have been deleted.