IEC 62343-3-3:2020 is available as IEC 62343-3-3:2020 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition.IEC 62343-3-3:2020 provides a performance specification template for wavelength selective switches. The object is to provide a framework for the preparation of detail specifications on the performance of wavelength selective switches. Additional specification parameters are often included for detailed product specifications or performance specifications if necessary. However, specification parameters specified in this document are not removed from the detail product specifications or performance specifications. The technical information regarding wavelength selective switches and their applications in DWDM systems with single-mode fibres are described in IEC TR 62343-6-4. This second edition cancels and replaces the first edition published in 2014. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: - modification of the normative references; - modification of the terms and definitions.