1.1 This specification covers high-strength, low-alloy, cold-rolled sheet and strip in cut lengths or coils, hot-rolled sheet and strip steel in cut lengths or coils with ordered thickness less than 0.230 in. [6.0 mm], and hot-rolled sheet coils (not cut lengths) with ordered thickness 0.230 in. [6.0 mm] and thicker, intended for use in structural and miscellaneous purposes, where savings in weight or added durability are important. These steels have enhanced atmospheric corrosion resistance and are supplied in three types or as commercial steel (CS). Type 2 contains 0.20 % minimum copper based on cast or heat analysis (0.18 % minimum Cu for product check). Type 4 and Type 5 contain additional alloying elements and provide a level of corrosion resistance substantially better than that of carbon steels with or without copper addition (Note 1). When properly exposed to the atmosphere, Type 4 and Type 5 steels can be used in the bare (unpainted) condition for many applications. CS is intended for applications that require enhanced atmospheric corrosion resistance which do not require a specified strength. CS shall contain the chemical requirements of Type 2, Type 4, or Type 5. CS as contained within this specification is not associated with the requirements of CS that are referenced in other Subcommittee A01.19 on Steel Sheet and Strip specifications.