Do not requisition an "XA" coded item Order its next higher assembly.
If an XB" item is not available from salvage, order it using the CAGEC and part number given.
Installation drawing, diagram, instruction sheet, field service drawing, that is identified by manufacturers
Item is not stocked Order an "XD" coded item through normal supply channels using the CAGEC 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 750-1.
Maintenance code. Maintenance codes tell you the category 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.
The maintenance code entered in the third position tells you the lowest maintenance category authorized to
remove, replace, and use an item. The maintenance code entered in the third position will indicate authorization to one of
the following categories of maintenance.
Crew or operator maintenance done within organizational oraviation maintenance.
Organizational or aviation unit category can remove, replace, and use the item.
Direct support or aviation intermediate category can remove, replace, and use the item.
General support category can remove, replace, and use the item.
Specialized repair activity can remove, replace, and use the item.
Depot category can remove, replace, and use the item.