This part of IEC 61280 provides uniform methods of measuring polarization mode dispersion (PMD) of single-mode installed links. An installed link is the optical path between transmitter and receiver, or a portion of that optical path. These measurements may be used to assess the suitability of a given link for high bit rate applications or to provide insight on the relationships of various related transmission attributes. This document focuses on the measurement methods and requirements for measuring long lengths of installed cabling that might also include other optical elements, such as splices, connectors, amplifiers, chromatic dispersion compensating modules, DWDM components, multiplexers, wavelength selective switches, ROADMS etc. PMD is a statistical parameter. The reproducibility of measurements depends on the particular method, but is limited also by the PMD level of the link and the accessible wavelength range. Gisin [1]1 derived a theoretical limit to this reproducibility independent of the measurement method by assuming ideal measurement conditions This document focuses on the apparatus, procedures, and calculations needed to complete measurements. IEC/TR 61282-9 explains the theory behind the test methods. Originally, the principles of edition 1 of this document were closely aligned with those of edition 1 of the optical fibre and optical fibre cable test method, IEC 60793-1-48 (see Bibliography), which focuses on aspects related to the measurement of factory lengths. However Edition 2 of IEC 60793-1-48 removed some of the test methods that are no longer of interest to fibre and cable manufacturers. These have been retained as informative Annexes D, E, and F in edition 2 of this document, and a new test method G has been added. Edition 2 of this document also updates test methods A, B and C and adds more information applicable to testing of installed cabling. NOTE 1 Test methods for factory lengths of optical fibres and optical fibre cables are given in IEC 60793-1-48. NOTE 2 Test methods for optical amplifiers are given in IEC 61290-11-1 and IEC 61290-11-2. NOTE 3 Test methods for passive optical components are given in IEC 61300-3-32. NOTE 4 Guidelines for the calculation of PMD for links that include components such as dispersion compensators or optical amplifiers are given in IEC/TR 61282-3. NOTE 5 Further general guidance on PMD measurements and background theory is contained in IEC/TR 61282-9. Edition 2 is being prepared in parallel with edition 2 of this standard.