This part of IEC 62074-1 applies to fibre optic wavelength division multiplexing (WDM) devices. These have all of the following general features: - They are passive, in that they contain no optoelectronic or other transducing elements; however they may use temperature control only to stabilize the device characteristics; they exclude any optical switching functions. - They have three or more ports for the entry and/or exit of optical power, and share optical power among these ports in a predetermined fashion depending on the wavelength. - The ports are optical fibres, or optical fibre connectors. This standard establishes uniform requirements for the following: - optical, mechanical and environmental properties. The responsible committee is Subcommittee DKE/K 412.7 "LWL-Verbindungstechnik und passive optische Komponenten" ("Fibre optic interconnecting devices and passive optical components") of the DKE (German Commission for Electrical, Electronic and Information Technologies) at DIN and VDE.