This European Standard specifies the characteristics and performance requirements for masonry units manufactured from clay for which the main intended uses are protected or unprotected masonry structure (see definitions 3.3 and 3.4) (e. g. facing and rendered masonry, loadbearing or non-loadbearing masonry structures, including internal linings and partitions, for building and civil engineering). This European Standard includes those clay masonry units of an overall non-rectangular parallelepiped shape. It defines the performance related to e. g. dimensional tolerances, strength, density measured according to the corresponding test methods contained in separate European Standards. It provides for the assessment and verification of constancy of performance (AVCP) of the product to this European Standard. The marking requirement for products covered by this European Standard is included. This European Standard does not specify standard sizes for clay masonry units, nor does it specify standard work dimensions, angles and radii of specially shaped clay masonry units. This European Standard does not include method of measurement of angles and radii characteristics of specially shaped clay masonry units. This European Standard does not cover requirements for the following: units for paving, flue liners and storey height clay masonry units and clay masonry units with an incorporated thermal insulation material bonded to the faces of the unit susceptible to be exposed to fire. It does, however, include clay masonry units for external chimney masonry.