XA--Do not requisition an "XA" -coded item. Order its next higher assembly. (Also, refer to the NOTE below.)
XB--If an "XB" item is not available from salvage, order it using the CAGE and part number given.
XC--Installation drawing, diagram, instruction sheet field service drawing, that is identified by manufacturer's part
XD--Item is not stocked. Order an 'XD' -coded item through normal supply channels using the CAGE and part number
given, if no NSN is available.
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 "XAU or those aircraft support items restricted by
requirements of AR 70042.
(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.
--Crew or operator maintenance done within unit or aviation unit
--Unit or aviation unit category can remove, replace, and use the item.
--Direct support or aviation intermediate level can remove, replace, and
use the item.
--General support level can remove, replace, and use the item.
--Specialized repair activity can remove, replace, and use the item.
--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: