TM 1-2835-209-23P (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 O - Aviation unit (AVUM) level can remove, replace and use the item. F - Aviation intermediate (AVIM) 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 - Aviation unit (AVUM) is the lowest level that can do complete repair of the item. F - Aviation intermediate (AVIM) 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 ad- justing, lubricating, etc, at the user level. 4