1.1 This specification covers gypsum, calcium sulfate combined with two molecules of water in crystalline form and having the approximate chemical formula CaSO4 [dot]2H2 O.

1.2 The values stated in either inch-pound units or SI (metric) are to be regarded separately as the standard. Within the text, the SI units are shown in brackets. The values stated in each system shall be used independently of the other. Values from the two systems shall not be combined.