This part of IEC 60672 is applicable to ceramic@ glass-ceramic@ glass-mica and glass materials for electrical insulating purposes. It provides@ for guidance@ a classification of materials for general electrical insulating purposes@ and indicates typical numerical values for the characteristics relevant to each subgroup or type of material as determined by the test methods defined in IEC 60672-2. These numerical values apply only to the specified test specimens and test methods. They cannot necessarily be extended to test specimens and products of other shapes and dimensions or methods of fabrication.