IEC 61300-3-14:2014(E) provides a method to measure the error and repeatability of the attenuation value settings of a variable optical attenuator (VOA). There are two control technologies for VOAs, manually controlled and electrically controlled. This standard covers both control technologies of VOAs and also covers both single-mode and multimode fibre VOAs. This third edition cancels and replaces the second edition published in 2006 and constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:- title modification replacing the word "accuracy" by "error";- inclusion of the distinction of manually and electrically controlled variable optical attenuators in the Scope;- revision of clauses for apparatus and details to be specified to harmonize with other standards in the IEC 61300 series;- addition of "the maximum deviation of attenuation from setting" to the clause for calculation;- addition of "measurement method of hysteresis characteristics" in Annex B. Keywords: attenuation value settings, variable optical attenuator (VOA)