IEC 62343:2017 applies to all commercially available optical dynamic modules and devices. It describes the products covered by the IEC 62343 series, defines terminology, fundamental considerations and basic approaches. The object of this document is to: establish uniform requirements for operation, reliability and environmental properties of dynamic modules (DMs) to be implemented in the appropriate DM standard, and provide assistance to the purchaser in the selection of consistently high-quality DM products for his particular applications, as well as in the consultation of the appropriate specific DM standard(s). This document covers performance templates, performance standards, reliability qualification requirements, hardware and software interfaces and related testing methods. Since a dynamic module integrates an optical module/device, printed wiring board, and software/firmware, the standards developed in the series will mimic appropriate existing standards. On the other hand, since dynamic module is a relatively new product category, the dynamic module standards series will not be bounded by the existing practices where requirements differ. The safety standards as related to dynamic modules are mostly optical power considerations, which is covered by IEC TC 76: Optical radiation safety and laser equipment. This second edition cancels and replaces the first edition published in 2013. This edition constitutes a technical revision. This edition includes the following significant technical change with respect to the previous edition: the inclusion of definitions for the wavelength selective switch.