IEC 60440:2012 specifies a method of measurement and associated test conditions to assess the magnitude of non-linear distortion generated in a resistor. This method is applied if prescribed by a relevant component specification, or if agreed between a customer and a manufacturer. This International Standard cancels and replaces the Technical Report IEC/TR 60440, published in 1973. The major changes with regard to the Technical Report are: - change of the principle parameter's term from "third harmonic attenuation" to "third harmonic ratio"; - addition of advice on the prescription of requirements in a relevant component specification; - addition of a set of recommended measuring conditions for a specimen with a rated dissipation of less than 100 mW; - a complete editorial revision.