ARMY TM 9-2815-260-24 AIR FORCE TO 38G1-126-2 MARINE CORPS TM 09244A/09245A-24 B-3/B-4 BLANK MAINTENANCE ALLOCATION CHART (Continued) d.(Cont) tasks identified for the maintenance functions authorized in the MAC.  The symbol designations for the various maintenance levels are as follows: C Operator or crew maintenance   O Unit maintenance F Direct support maintenance H General support maintenance D Depot maintenance e.   Column 5,  Tools and Test Equipment reference code.  Column 5 specifies, by code, those common tool sets (not individual tools), common TMDE, and special tools, special TMDE, and support equipment required to perform the designated function. Codes are keyed to tools and test equipment in section III.   f.    Column 6,  Remarks.    When applicable, this column contains a letter code, in alphabetic order, which shall be keyed to the remarks contained in section IV. B.4   Explanation of columns in Tool 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 Level.  The lowest level 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, model number, or type number. B.5  Explanation of Columns in Remarks,  Section IV a.   Column 1, Remarks  Code.  The code recorded in column 6, section II. b.   Column 2,   Remarks.  This column along with the related codes should be used to clarify maintenance and inspection functions by different MOSs involved in maintaining some components.