The standard A860 is more strict in both chemical and mechanical requirements, you can use WPHY 42, 46 and maybe WPHY 52 as WPL6 , when the tensile strength is not over 95 ksi, the yield strength,elongation and charpy values are lower for WPL6 with not maximum values. The WPL3, WPL8 and WPL9 are different material, the chemical requirements are different. About the marking all depends in the supplier and customer agreement