This International Standard is applicable to portable and transportable contamination meters and monitors designed for the direct measurement or the direct detection of surface contamination by photon radiation emitting radionuclides and which comprise at least: – a detection assembly (comprising counter tube, scintillation detector or semiconductor detector, etc.), which may be connected either rigidly or by means of a flexible cable or incorporated into a single assembly; – a measurement assembly. The standard is applicable to: – photon surface contamination meters; – photon surface contamination monitors. The standard is applicable to detection assemblies that are designed to measure photon contamination from radionuclides which emit photons with energy in excess of 5 keV. In particular, this standard should be used to assess the performance of assemblies used to demonstrate that material is free from surface contamination by photon emitting radionuclides. This standard is also applicable to special purpose assemblies and to assemblies specifically designed to provide limited spectroscopic information to the user. NOTE These detection assemblies may be used to measure photon emissions from radionuclides that also emit alpha and beta radiations, where the alpha and beta emissions may be shielded due to the nature of the contamination. If shielding of the radioactive emissions occurs, then strictly speaking, the contamination is near to rather than on the surface of the article being monitored. The object of this standard is to lay down standard requirements and to give examples of acceptable methods, and also to specify general characteristics, general test conditions, radiation characteristics, electrical safety, environmental characteristics, and the requirements of the identification certificate for photon contamination meters and monitors.