TM 10-5411-232-13&P CARGO BED COVER (CBC) M105A2 TRAILER, TYPE II 0021 00 MAINTENANCE ALLOCATION CHART (MAC) Explanation of Columns in the MAC Column (1) - Group Number.  Column (1) lists Functional Group Code (FGC) numbers, the purpose of which is to identify maintenance significant components, assemblies, subassemblies, and modules with the Next Higher Assembly (NHA).  End item group numbers are “00”. Column (2) - Component/Assembly.  Column (2) contains the names of components, assemblies, subassemblies, and modules for which maintenance is authorized. 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, refer to “Maintenance Functions” outlined previously). 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 manhours 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 the complexity of the tasks within the listed maintenance function vary at different maintenance levels, appropriate work time figures are to be 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 MAC.   The symbol designations for the various maintenance levels are shown as follows: C .......  Operator or Crew Maintenance     H .......  General Support Maintenance O .......  Unit Maintenance D .......  Depot Maintenance F .......  Direct Support Maintenance Column (5), Tools and Equipment Reference Code.  Column (5) specifies, by code, those common tool sets (not individual tools) common Test, Measurement and Diagnostic Equipment (TMDE), and special tools, special TMDE, and special support equipment required to perform the designated function. Column (6), Remarks Code.  When applicable, this column contains a letter code, in alphabetical order, which is keyed to the remarks contained in Table 3. Explanation of Columns in the Tools and Test Equipment Requirements Column (1) - Tool or Test Equipment Reference Code.  The tool or test equipment reference code correlates with a code used in column (5) of the MAC. Column (2) - Maintenance Level.  The lowest level of maintenance authorized to use the tool or test equipment. 0021 00-3