This part of ISO 7146 defines, describes and classifies the characteristics of damage occurring in service in hydrodynamically lubricated metallic plain bearings due to cavitation erosion, together with possible countermeasures. It assists in understanding the various characteristic forms of damage which may occur. Consideration is restricted to damage which has a well-defined appearance and which can be attributed to particular causes with a high degree of certainty. Various appearances are illustrated with photographs and diagrams.