MIL-S-7742D, MILITARY SPECIFICATION: SCREW THREADS, STANDARD, OPTIMUM SELECTED SERIES: GENERAL SPECIFICATION FOR (25 JUL 1991) [NO S/S DOCUMENT]., This specification covers the requirements for a selected series of standard Unified and Unified Miniature screw threads, classes 3A and 3B of Fed-std-H28/2 and FED-STD-H28/5 for general aerospace and similar high-tech application.