TM 10-6640-215-13 the specific tasks identified for the maintenance functions authorized in the maintenance allocation chart.  The system designations for the various maintenance levels are shown on the following page. C Operator or crew 0 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) common TMDE, and special tools, special TMDE, and support equipment required to perform the designated function. f. Column 6, Remarks.  This column, when applicable, contains a letter code, in alphabetic order, which is keyed to the remarks contained in Section IV. B-4.  EXPLANATION OF COLUMNS IN TOOL AND TEST EQUIPMENT REQUIREMENTS, SECTION Ill. 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 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