IEC 61275:2013 is applicable to a portable or transportable photon spectrometry assembly using a high purity germanium (HPGe) detector to survey, in situ, generally at 1 m above ground level, areas in the environment for discrete radionuclides. This standard specifies for such an assembly the general characteristics and test methods for evaluating radiation, electrical, mechanical, safety and environmental characteristics specific to the applications described above. Advice is also provided in annexes as to the calibration, appropriate use and interpretation of the system for in situ measurements. The main technical changes with regard to the previous edition are as follows: