ASTM A354 is an ASTM International standard that defines chemical and mechanical properties for alloy steel bolts, screws, studs, and other externally threaded fasteners.
It is officially titled: Standard Specification for Quenched and Tempered Alloy Steel Bolts, Studs, and Other Externally Threaded Fasteners.
This standard defines the properties for fasteners up to 4 inches in diameter.
In those applications structural heavy hex bolts are to be used, as defined by ASTM A490, even though they have the same strength.
[1][2] The standard also specifies what nuts are recommended for use with the defined fasteners.