This document deals with geometrical defects that may be present on the surfaces of material measures and calibration specimens conforming to ISO 5436-1 and ISO 25178-70. It defines classes of these geometrical defects, 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 minimise the uncertainty of their own measurements; NOTE Such policies are required in ISO 17025-5.4.2:2005 selection of methods, 5.7.1 sampling procedures, and 5.10.2 h), for example. c) to enable calibration laboratories and their customers to agree 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 to be avoided in measurement.