Relates to the handling of logarithmic quantities, without regard to their interpretation or specific application. Deals with: logarithmic quantities (transmission path quantities, levels, frequency interval, quantities related to information content), units for logarithmic quantities (neper and bel, octave and decade, Shannon, Hartley and natural unit of information, multiples of units), numerical values of logarithmic quantities, logarithmic quantities with unit, notation for expressing the reference of a level.