IEC 61753-085-02:2021 contains the minimum initial test and measurement requirements and severities which a fibre-optic pigtailed coarse wavelength division multiplexing (CWDM) device satisfies in order to be categorised as meeting the requirements of category C (indoor controlled environment), as defined in Annex A of IEC 61753-1:2018. CWDM is defined in IEC 62074‑1.