ARMY TM 10-1670-271-23&P
AIR FORCE TO 14D1-2-464-2
MARINE CORPS TM 01136B-23&P/1
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 Code and part number given.
XC - Installation drawing, diagram, instruction sheet, field service drawing, that is identified by manufacturer's
XD - Item is not stocked. Order an "XD"-coded item through normal supply channels using the CAGE Code
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 00-42.
(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 third and fourth positions of the SMR code
(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 the following levels of maintenance.
C - Crew or operator maintenance done within organizational or aviation unit maintenance.
O - Organizational or aviation unit can remove, replace, and use the item.
F - Direct support or aviation intermediate level can remove, replace, and use the item.
H - General support maintenance can remove, replace, and use the item.
L - Specialized repair activity can remove, replace, and use the item.
D - Depot can remove, replace, and use the item.