This specification covers cast carbon and alloy steel ingots and strand castings, semi-wrought ingots and strand castings and rolled or forged blooms, billets, and slabs for forging. Blooms, billets, and slabs are semi-finished steel products, hot rolled or forged to approximate cross-sectional dimensions. Blooms and billets may be square, round, octagonal, or rectangular in section; slabs are rectangular. Although no invariable rule prevails between the terms blooms and billets, and they are frequently used interchangeably, the following size distinctions are in general use. Blooms - Cross-sectional area greater than 36 in.2 (232 cm2 ). Billets - Maximum cross-sectional area 36 in.2 (232 cm2). Slabs - Minimum thickness, 11/2 in. (38.0 mm); width, more than twice the thickness; and generally a cross-sectional area of not less than 16 in. 2 (103 cm2). Ingots either top or bottom poured or secondary remelted are covered. Strand castings with or without additional reduction are covered. Supplementary requirements (S1 to S19) of an optional nature are provided. They shall apply only when specified by the purchaser. The values stated in inch-pound units are to be regarded as the standard.