TM 9-2815-225-34&P (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 follow: Code Explanation PA Stocked items: use the applicable NSN to request/requisition items PB with these source codes.  They are authorized to the category PC** indicated by the code entered in the 3d position of the SMR code. PD PE ** NOTE:  Items coded PC are subject to deterioration. PF PG KD Items with these codes are not to be requested/requisitioned KF individually.  They are part of a kit which is authorized to the KB maintenance category indicated in the 3d position of the SMR code. The complete kit must be requisitioned and applied. MO - (Made at Unit Level) Items with these codes are not to be requested/requisitioned MF - (Made at DS Level) individually.  They must be made from bulk material which is MH - (Made at GS Level) identified by the part number in the DESCRIPTION AND USABLE ML - (Made at Specialized ON CODE (UOC) column and listed in the bulk material group of Repair Activity (SPA)) the repair parts list in the RPSTL.  If the item is authorized to you MD - (Made at Depot) 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 Unit Level) Items with these codes are not to be requested/requisitioned AF - (Assembled by DS Level) individually.  The parts that make up the assembled item must be AH - (Assembled by GS Level) requisitioned or fabricated and assembled at the level of AL - (Assembled by SRA) maintenance indicated by the source code.  If the 3d position code of AD - (Assembled by Depot) the SMR code authorizes you to 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. XA - Do not requisition an XA-coded item.  Order its next higher assembly.  (Also refer to the note below.) XB - If an XB-coded item is not available from salvage, order it using the CAGEC and part number given. XC - Installation drawing, diagram, instruction sheet, field service drawing, that is identified by manufacturer's part number. XD - 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. NOTE 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. (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 3d and 4th positions of the SMR code as follows: (a) The  maintenance  code  entered  in  the  3d  position  tells  you  the  lowest  maintenance  level  authorized  to  remove, replace, and use an item.  The maintenance code entered in the 3d position will indicate authorization to one of the following levels of maintenance. Code Application/Explanation C - Crew or operator maintenance done within unit maintenance. O - Unit level can remove, replace, and use the item. F - Direct support 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. D - Depot level can remove, replace, and use the item. B-2