Split heads and head bursts on threaded metal fasteners are classified as “surface discontinuities.” As such, they fall under the jurisdiction of quality standards such as ASTM F788/788M and SAE J1061. These and similar standards use the same criteria to classify and specify allowable limits of surface discontinuities that occur while manufacturing and processing bolts, screws, studs, and other types of externally threaded fasteners. Although these standards do not specifically refer to rivets, they are also applicable to rivets.(…)
via Preventing Seams and Head Bursts in Threaded Metal Fasteners.