IEC 61167:2015 specifies the performance requirements for metal halide lamps for general lighting purposes. This third edition replaces the second edition published in 2011. This third edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition. a) A set of new lamp data sheets (20 W, 35 W, 50 W, 100 W) is introduced. b) Reference to ILCOS (International lamp coding system) is removed from the lamp data sheets and now located in a new annex. c) Information on outer bulb temperature (and in some cases also on pin temperature and temperature adjacent to cap) is replaced with an explanation on differences in manufacturers' construction; this explanation is given in detail in a new annex.