TM 5-3810-303-24P Code Application/Explanation PA Stocked items; use the applicable NSN to request/requisition items with these source codes.  They are PB authorized to the category indicated by the code entered in the 3d position of the SMR code. PC** **Items coded PC are subject to deterioration. PD PE PF KD Items with these codes are not to be requested/requisitioned individually. They are part of a kit  which is KF authorized to the maintenance category indicated in the 3d position of the SMR code.  The complete kit KB must be requisitioned and applied. MO-(Made at UM Items with these codes are not to be requested/requisitioned individually. AVUM Level) They must be made from bulk material which is identified by the part number in MF-(Made at DS/ the DESCRIPTION AND USABLE ON CODE (UOC) column and listed in the AVUM Level) Bulk Material group of the repair parts list in this RPSTL.  If the item is MH-(Made at GS authorized to you by the 3d position code of the SMR code, but the Level) source code indicates it is made at a higher level, order the item from the ML-(Made at Specialized Repair higher level of maintenance. Activity (SRA)) MD-(Made at Depot) AO- (Assembled by Items with these codes are not to be requested/requisitioned individually.  The UM/AVUM Level) parts that make up the assembled item must be requisitioned or fabricated and AF - (Assembled by assembled at the level of maintenance indicated by the source code.  If the 3d DS/AVIM Level) position code of the SMR code authorizes you to replace the item, but the AH - (Assembled by source code indicates the item is assembled at a higher level, order the item GS Category) from the higher level of maintenance. AL - (Assembled by SRA) AD - (Assembled by Depot) XA - Do not requisition an “XA”-coded item.  Order its next higher assembly.  (Also, refer to the NOTE following.) 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  with the above source codes, except for those source 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 maintenance. Code Application/Explanation C - Crew or operator maintenance done within unit maintenance or aviation unit maintenance. O - 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. D - 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: 2