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 FSCM and part number given.
XC - Installation drawing, diagr am, 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 FSCM 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
"XA" or those aircraft support items restricted by requirements of AR 700-42.
(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 maintenance.
-Unit maintenance level can remove, replace, and use the item.
-Intermediate (DS) level can remove, replace, and use the item.
-Intermediate (GS) 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.
-Unit maintenance is the lowest level that can do complete repair of the item.
-Intermediate (DS) is the lowest level that can do complet e repair of the item.