(1) Source Code. The source code tells you how to get an item needed for maintenance, repair, or overhaul of an
end item/equipment. Explanations of source codes follows:
Stocked items; use the applicable NSN to request/requisition items with these source codes. They are
authorized to the category indicated by the code entered in the 3d position of the SMR code.
**Items coded PC are subject to deterioration.
Items with these codes are not to be requested/requisitioned individually. They are part of a kit which is
authorized to the maintenance category indicated in the 3d position of the SMR code. The complete kit
must be requisitioned and applied.
MO-(Made at UM/AVUM Level)
Items with these codes are not to be requested/requisitioned
MF-(Made at IDS/AVUM Level)
individually. They must be made from bulk material which is identified by
MH-(Made at IGS Level)
the part number in the DESCRIPTION AND USABLE ON CODE (UOC)
ML-(Made at Specialized Repair Act (SRA))
column and listed in the Bulk Material group of the repair parts list in this
MD-(Made at Depot
RPSTL. If the item is authorized to you by the 3d position code of the SMR
code, but the source code indicates it is made at a higher level, order the
item from the higher level of maintenance.
AO-,/Assembled by UM/AVUM Level)
Items with these codes are not to be requested/requisitioned individually.
AF-(Assembled by IDS/AVIM Level)
The parts that make up the assembled item must be requisitioned or
AH-(Assembled by IGS Category)
fabricated and assembled at the level of maintenance indicated by the
AL-(Assembled by SRA)
source code. If the 3d position code of the SMR code authorizes you to
AD-(Assembled by Depot)
replace the item, but the source code indicates the item is assembled at
a higher level, order the item from the higher level of maintenance.
Do not requisition an "XA"-coded item. Order its next higher assembly.
(Also, refer to the NOTE below.)
If an "XB" item is not available from salvage, order it using the FSCM and
part number given.
Installation drawing, diagram, instruction sheet, field service drawing, that
is identified by the manufacturers part number.
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.
NOTE: Cannibalization or controlled exchange, when authorized, may be used as source of supply for items with the
above source codes, except for those source coded "XAW or those aircraft support items restricted by requirements of AR
(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 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 or aviation unit maintenance.
Unit maintenance 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: