ARMY   TM   9-2815-253-24P AIR  FORCE  TO  38G1-93-4 MARINE  CORPS  TM  2815-24P/1 3 EXPLANATION   OF   COLUMNS   (SECTIONS   II   AND   III).   (Continued NOTE: Cannibalization or controlled exchange, when authorized, may be used as a source of supply for items with the above source codes, except for those source coded ‘XA” or those aircraft support items restricted by requirements of AR 700-42. (2)   Maintenance   Code. Maintenance codes tell you the level(s) of maintenance authorized to USE and REPAIR support items. The maintenance codes are entered in the 3rd and 4th positions of the SMR Code as follows: (a) The  maintenance  code  entered  in  the  3rd  position  tells  you  the  lowest  maintenance  level  authorized to remove, replace, and use an item. The maintenance code entered in the 3rd position will indicate authorization to one of the following levels of maintenance. Code Application/Explanation C -Crew or operator maintenance done within organization or aviation  unit  maintenance. 0 -Organizational or aviation unit category can remove, replace, and use the item. F -Direct support or aviation intermediate level can remove, replace, and use the item. H General support level can remove, replace, and use the item. L -Specialized repair activity can remove, replace, and use the item. D -Depot level can remove, replace, and use the item. The maintenance code entered in the 4th position tells whether or not the item is to be repaired and identifies the lowest maintenance level with the capability to do comptete repair (i.e.. perform all authorized repair functions.) (NOTE: Some limited  repair  may  be  done  on  the  item  at  a  lower  level  of  maintenance,  if  authorized  by  the  Maintenance  Allocation  Chart (MAC) and SMR Codes.) This position will contain one of the following maintenance codes. 4