MS-573 has the following title: CARBON STEEL - AISI 1010, 1212, 1213M, 1215 OR 12L14. It then states "SEE MS-BAR". MS-BAR has the following description for MS-573:
Cold Formed parts shall be fabricated from MS-420 Steel (SAE 1010). Parts machined from bar stock may use these optional materials MS-200 (SAE 1212) and MS-420 (SAE 1010), MS-760 (SAE 1213 or 1215) and MS-3395 (SAE 12L14).