This part of ISO 7503 applies to the evaluation of contamination on surfaces of facilities and equipment, containers of radioactive materials and sealed sources in terms of activity per unit area. It does not apply to the evaluation of contamination of skin or clothing. It is restricted to the direct measurement by portable probes and to the indirect measurement of the radionuclides mentioned in the Introduction and listed in table A.1 of annex A. For each radionuclide, the energy spectrum as well as the intensity of each type of emitted particle of photon is unique. This type of information can be found in the bibliographic references given in annex F. For the purpose of this part of ISO 7503, the term "beta energy" refers to th e maximum energy of particles from classical beta decay. NOTE - Evaluation of surface contamination by beta-emitters (beta energy greater than 0,15 MeV) and alpha-emitters is dealt with in ISO 7503-1. Evaluation of tritium surface contamination of dealt with in ISO 7503-2.