This document defines classes of geometrical defects that might be present on the surfaces of material measures and calibration specimens conforming to ISO 5436-1 and ISO 25178-70, and defines terms for ways of responding to these defects. This document is applicable as follows: a) to help customers and users of material measures for surface metrology specify their nominal features (ideal geometrical properties) when obtaining them from manufacturers and suppliers; b) to enable users of material measures to formulate their own rules and policies for responding to the occurrence of defects in such a way as to minimize the uncertainty of their own measurements; NOTE Such policies are required in ISO/IEC 17025:2017, 7.2.1.1, 7.2.1.3, 7.3.1 and 7.8.5 c) and d), for example. c) to enable calibration laboratories and their customers to agree on a common policy on how to treat defects on a material measure that has been sent for calibration; d) to educate users of material measures about the different significance and importance of different kinds of defect; e) for other GPS standards which make reference to the issue of selection of measuring locations, or selection of areas to be measured or avoided in measurement.