Cement. United States Government master specification for cement, plastic magnesia (magnesia-oxychloride), used as flooring, bases, wainscots, etc., Federal Specifications Board Specification 445, officially promulgated by Federal Specifications Board, Oct. 28, 1926, for use of Departments and independent establishments of Government in purchase of plastic magnesia cement (magnesia-oxychloride) used as flooring, bases, wainscots, etc.