- This document specifies the characteristics and performance requirements of calcium silicate masonry units for which the main intended uses are inner walls, outer walls, cellars, foundations and external chimney masonry. - It defines the performance related to e.g. strength, density and dimensional accuracy, measured according to the corresponding test methods contained in separate Gulf Standard .It provides for the evaluation of conformity of the product to this Gulf Standard. - The marking requirement for products covered by this document is also included . - This document does not specify standard sizes for calcium silicate masonry units. ( Note: For information on sizes and shapes BS4729 may be referred ). - It does not cover units with more than 60 % volume of voids, nor products made from shale as a major raw material. - It covers specially shaped masonry units also , which are not regular parallel piped.