TM 10-5430-240-13&P 0028 00 0028 00-2 Source Code.  The source code tells you how you get an item needed for maintenance, repair, or overhaul of an end item/equipment.  Explanations of source codes follow. Source Code     Application/Explanation PA   Stocked items; use the applicable NSN to   PB   request/requisition items with these   PC source codes.  They are authorized   PD to the level indicated by the code PE entered in the 3rd position of the SMR code. PF PG             NOTE Items coded PC are subject to deterioration. KD Items with these codes are not to be KF requested/requisitioned individually.  They KB   are part of a kit which is authorized to the   maintenance level indicated in the 3rd position of the SMR code.  The complete   kit must be requisitioned and applied. MO-Made at unit/ Items with these codes are not to be requested/ AVUM level requisitioned individually.  They must be made MF-Made at DS/ from bulk material which is identified by the P/N AVIM level in the DESCRIPTION AND USABLE ON CODE MH-Made at GS (UOC) column and listed in the bulk material level group work package of the RPSTL.  If the item ML-Made at SRA is authorized to you by the 3^rd position code of MD-Made at depot the SMR code, but the source code indicates   it is made at higher level, order the item from the higher level of maintenance. AO-Assembled by Items with these codes are not to be   unit/AVUM level requested/requisitioned individually.  The parts AF-Assembled by that make up the assembled item must be DS/AVIM level                                                     requisitioned or fabricated and assembled at the AH-Assembled by   level of maintenance indicated by the source code. GS level   If the 3rd position of the SMR code, authorizes you AL-Assembled by to replace the item, but the source code indicates SRA   the item is assembled at a higher level, order the   AD-Assembled by   item from the higher level of maintenance. depot    XA    Do not requisition an "XA" coded item.  Order the next higher assembly.  (Refer to the NOTE below.)   XB    If an item is not available from salvage, order it using the CAGEC and P/N.   XC    Installation drawings, diagrams, instruction sheets, field service drawings; identified by manufacturer's P/N.                XD    Item is not stocked.  Order an XD-coded item through normal supply channels using the CAGEC and P/N given, if no NSN is available.