TM 10-351 0-220-24P 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 750-1. (2) Maintenance  Code.     Maintenance  codes  tells  you  the  level(s)  of  maintenance  authorized  to  USE  and REPAIR support items.  The maintenance codes are entered in the third and fourth positions of the SMR code as follows: (a) The maintenance code entered in the third position tells you the lowest maintenance level authorized to remove,  replace,  and use an item The maintenance code entered In the third position will indicate authorization to one of the following levels of maintenance. Code Application/Explanation C - Crew or operator maintenance done within organizational or aviation unit maintenance O - 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 (b) The maintenance code entered in the fourth position tells whether or not the Item Is to be repaired and identifies  the  lowest  maintenance  level  with  the  capability  to  do  complete  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. Code   Application/Explanation O - Organizational or (aviation unit) is the lowest level that can do complete repair of the item F - Direct support or aviation Intermediate Is the lowest level that can do complete repair of the item H - General Support is the lowest level that can do complete repair of the Item L - Specialized repair activity Is the lowest level that can do complete repair of the Item D - Depot Is the lowest level that can do complete repair of the Item Z - Nonreparable  No repair is authorized B - No repair Is authorized  (No parts or special tools are authorized for the maintenance of a "B" coded item) However,  the Item may be reconditioned by adjusting,  lubricating,  etc,  at the user level (3)    Recoverability Code.    Recoverability codes are assigned to items to indicate the disposition action on unserviceable items.  The recoverability code is entered in the fifth position of the SMR Code as follows: 3