TM 5-3815-228-12&P SECTION I (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 Code Application/Explanation PA Stocked items; use the applicable NSN to PB request/requisition items with these PC** source codes.  They are authorized to the PD category indicated by the code entered in PE 3d position of the SMR code. PF PG **Items coded PC are subject to deterioration KD Items with these codes are not to be KF requested/requisitioned individually.. KB is part of a kit, which is authorized to the maintenance category indicated in the 3d position of the SMR code. The complete kit with the above source codes, except for those source must be requisitioned and applied. MO-(Made at UMItems with these codes are not AVUM Level) to be requested/ requisitioned MF-(Made at DS/ individually.  They must be made from bulk material which is identified by the part number in the AVUM Level) DESCRIPTION AND USABLEON CODE OC) column and listed in the Bulk Material group of the repair parts list in this ML-(Made at Specialized Repair RPSTL.  If the item is authorized- Act (SRA)) to you by the 3d position code of the SMR code, but if the MD-(Made at source code indicates it is made Depot) at a higher level, order the item from the higher level of maintenance. AO-(Assembled by Items with these codes are not UM/AVUM Level)to be requested/requisitioned individually.  The parts that AF-(Assembled by make up the assembled item DS/A VIM Level)  must be requisitioned or fabricated and assembled at the level AH-(Assembled by of maintenance indicated by GS Category) the source code.  If the 3d position code of the SMR code by AL-(Assembled by authorizes you to replace the SRA) item, but the source code indi- AD-(Assembled   cates the item is assembled at a by Depot) bled at a higher level, order the item from the higher level of maintenance. 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 the manufacturer's part number. 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. NOTE: Cannibalization or controlled exchange, when authorized may be used as source of supply for items coded "XA" or those aircraft support items restricted by requirements of AR 700-42. (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 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 main- Code Application/Explanation C- Crew or operator maintenance done within unit or aviation unit maintenance 0- Unit maintenance or aviation unit category can remove, replace and use the item F- Direct support or aviation intermediate level can remove, replace and use the item H- General support level can remove, replace and use the item L- Specialized repair activity can remove, replace and use the item. A-2