The purpose of this standard is to give, in table form, the quantities and units of heat. When two or more symbols are given for the same quantity, without special dis inction, they can be used indifferently. SI units are given in bold; other units are given in common characters. The abbreviations "ni, de, en" mean "Dutch, German, Englis " respectively (is 639:1988). Appendix A provides units for use in specific areas. The definitions of the units are given in the NBN X 02-001 standard.