This Standard covers general and dimensional datapertinent to the various types of screw and captivewasher assemblies, otherwise known as SEMS. SEMSproducts may include screws, tapping screws, or boltsin sizes No. 0 through 1/2 in. diameters in various gradesand materials. The word SEMS is recognized in theUnited States as a generic term applicable to screw andwasher assemblies. Also included in this Standard isNonmandatory Appendix A illustrating the relativeproportions of plain and conical washer SEMS.