TM10-3930-660-20 d. Column 4, Maintenance Category. This column specifies, by the listing of a work time figure in the appropriate subcolumn(s), the highest category of maintenance authorized to perform the function listed in Column 3. This figure represents the active time required to perform that maintenance function at the indicated category of maintenance. If the number or complexity of the tasks within the listed maintenance function vary at different maintenance categories, appropriate work time figures will be shown for each category. 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/quality control 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 categories are as follows: SYMBOL MAINTENANCE  CATEGORY c   .  . . . . . .  . . . . . .  . . . . . . . .  . .  . .   Operator or Crew o   . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Organizational  Maintenance F . . . . .  .  . . . . . . . . . . . . . . . . . . . . . . . Direct Support Maintenance H . . . . . . . . . . . . . . . . . . . .   General  Support  Maintenance D   .  .  . .  . . . .  . . . . . . ...  . .  . .   Depot  Maintenance e. Column 5, Tools and Equipment. This column specifies, by code, those common tool sets (not individual tools) and special tools, test, measurement and diagnostic equipment (TMDE) , and support equipment required to perform the designated function. f. Column  6,  Remarks.  This  column  will,  when  applicable,  contain  a  reference 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. This column lists the correlates with a code used in the MAC, Column 5, Section II. b. Column 2, Maintenance Category. This column lists the lowest category of maintenance authorized to use the tool or test equipment. c. Column 3, Nomenclature. This column lists the Federal item name or identification of the tool or test equipment. d. Column 4, National/NATO Stock Number. This column lists the NSN of the tool or test equipment, if available. e. Column 5, Tool Number. This column lists the manufacturer’s part number for the tool or test equipment. B-3