Applies to all commercially available optical amplifiers (OAs) including those using fibres (OFAs), semiconductors (SOAs), and waveguides (POWA), as classified in IEC 61292-3. This Technical Report presents general information about polarization mode dispersion (PMD), related to the application of the two commonly used methods to test PMD in OAs, the Jones matrix eigenanalysis (JME) and the Poincaré sphere analysis (PSA). This report is complementary to the International Standards describing the JME procedure (IEC 61290-11-1) and the PSA procedure (IEC 61290-11-2).