Symbols and designations: letter symbols associated with screw threads are of two kinds.
A. dimensional symbols: letter symbols for the designating dimensions of screw threads and threaded products. These are standard alpha numeric symbols to designate the dimensions of screw threads in text.
B. thread designation: abbreviations used as designations for various standard thread forms, thread series, and feature designations for use on drawings. Thread series designations are capital letter abbreviations of names used on drawings, in tables, and otherwise to designate various forms of thread and thread series. They commonly consist of combinations of such abbreviations. These are assembled in Appendix A, which include the names and abbreviations that are now in use, together with references to standards in which they occur for various standard threads.
Original Posting: 3/20/2012
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