ARMY TM 9-2815-257-24 AIR FORCE TO 38G1-128-2 MARINE CORPS TM 10155A/2815-24/3 B-3 c.    Column 3, Maintenance Function.  Column 3 lists the functions to be performed on the item listed in Column 2.  (For detailed explanation of these functions, see paragraph B-2). d.    Column 4, Maintenance Level.  Column 4 specifies each level of maintenance authorized to perform each function listed in Column 3, by indicating work time required (expressed as man-hours in whole hours or decimals) in the appropriate subcolumn.  This work-time figure represents the active time required to perform that  maintenance  function  at  the  indicated  level  of  maintenance.    If  the  number  or  complexity  of  the  tasks within the listed maintenance function vary at different maintenance levels, appropriate work-time figures are shown for each level.  The work-time figure represents the average time required to restore an item (assembly, subassembly, component, module, end item, or system) to a serviceable condition under typical field operating conditions.      This   time   includes   preparation   time   (including   any   necessary   disassembly/assembly   time), troubleshooting/fault location time, and quality assurance time in addition to the time required to perform the specific  tasks  identified  for  the  maintenance  functions  authorized  in  the  maintenance  allocation  chart.    the symbol designations for the various maintenance levels are as follows: C    Operator or crew maintenance O Unit maintenance F     Direct support maintenance L    Specialized Repair Activity (SRA)(5) H    General support maintenance D Depot maintenance e. Column 5, Tools and Test Equipment Reference Code.  Column 5 specifies the common tool sets (not individual tools), common TMDE, special tools, special TMDE, and special 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  alphabetical  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  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. (5)  This  maintenance  level  is  not  included  in  Section  II,  Column  4  of  the  MAC.   Functions  to  this  level  of maintenance are identified by a work-time figure in the "H" column in Section II, Column 4, and an associated reference  code  is  used  in  the  Remarks  column.    This  code  is  keyed  to  Section  IV,  remarks,  and  the  SRA complete repair application is explained there.