ISO 15548-1:2013 identifies the functional characteristics of a general-purpose eddy current instrument and provides methods for their measurement and verification. The evaluation of these characteristics permits a well-defined description and comparability of eddy current equipment. By careful choice of the characteristics, a consistent and effective eddy current examination system can be designed for a specific application. Where accessories are used, these are characterized using the principles of ISO 15548-1:2013. ISO 15548-1:2013 gives neither the extent of verification nor acceptance criteria for the characteristics. They are given in the application documents.