TM    10-4930-248-13&P B-3.   EXPLANATION OF COLUMNS   IN  THE  MAC  - SECTION II  - continued. 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 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   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