TM 10-3930-669-20 C.............................................................................. Operator or crew O.............................................................................. Unit Maintenance F .............................................................................. Direct Support Maintenance H.............................................................................. General Support Maintenance D.............................................................................. Depot Maintenance e. Column 5, Tools and Equipment.    Column  5  specifies,  by  code,  those  common  tool  sets  (not  individual tools) and special tools, TMDE, and support equipment required to perform the designated function. f. Column 6, Remarks.  This column shall, when applicable, contain a letter code, in alphabetic order, which shall be keyed to the remarks contained in Section IV. B-4.  EXPLANATION OF COLUMNS IN TOOLS AND TEST EQUIPMENT REQUIREMENTS, SECTION III. a. Column 1, Reference Code.  The tool and test equipment reference code correlates with a code used in the MAC, Section II, Column 5. b. Column 2, Maintenance Category.  The lowest category of maintenance authorized to use the tool or test equipment. c. Column 3, Nomenclature.  Name or identification of the tool or test equipment. d. Column 4, National Stock Number.  The national stock number of the tool or test equipment. e. Column 5, Tool Number.  The manufacturer's part number. B-5.  EXPLANATION OF COLUMNS IN REMARKS, SECTION IV. a. Column 1, Reference Code.  The code recorded in column 6, Section II. b. Column 2, Remarks.  This column lists information pertinent to the maintenance function being performed as indicated in the MAC, Section II. B-3