IEC/TS 62538:2008(E) which is a technical specification, applies to optical devices (i.e. elements, components, assemblies, sub-assemblies or modules) of interest to TC86 and its subcommittee. It provides the definitions of the three main categories of optical devices (i.e. dynamic, active and passive) together with other related definitions. It also gives a general procedure to identify the category of any optical devices.