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FED-STD-H28/1B NOT 1
Screw-Thread Standards for Federal Services Section 1 Nomenclature, Definitions and Letter Symbols for Screw Threads
This section establishes uniform practices with regard to screw thread nomenclature and letter symbols for designating characteristics of screw threads. These are for use on drawings, in tables of dimensions which set forth dimensional standards and in other records, and for expressing mathematical relationships.
Department of Defense [dod]