This part of IEC 61300 describes the measurement methods necessary to characterise the group delay properties of passive devices and dynamic modules. From these measurements further parameters like group delay ripple, linear phase deviation, chromatic dispersion, dispersion slope, and phase ripple can be derived. In addition, when these measurements are made with resolved polarization, the differential group delay can also be determined as an alternative to separate measurement with the dedicated methods of IEC 61300-3-32.