CISPR/TR 31:2012 covers the rationale behind the actual database covering the characteristics of radio services. The objective of the database is to register those characteristics which are relevant for derivation and specification of limits for disturbance emissions from electric and/or electronic equipment, systems and installations. Committees responsible for generic and/or product emission EMC standards should use this information together with CISPR 23. This second edition includes the replacement of CISPR 23 as reference standard for the determination of limits by CISPR 16-4-4:2007 on "model for the calculation of limits for the protection of radio services".