This European Standard specifies the characteristics and performance requirements for masonry units manufactured from clay for use in masonry construction (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 is intended to apply to two groups of fired-clay masonry units:a) LD units (see 3.4 and 5.2) comprising:1) clay masonry units with a gross dry density of less than or equal to 1 000 kg/m3 for use in protected masonry.b) HD units (see 3.5 and 5.3) comprising:1) all clay masonry units for use in unprotected masonry;2) clay