TM 10-3930-625-24P Code Application/Explanation PA Stocked items; use the applicable NSN to PB request/requisition items with these source PC** codes.  They are authorized to the category PD indicated by the code entered in the 3d PE position of the SMR code. PF **  Items  coded  PC  are  subject  to PG deterioration. Items with these codes are not to be KD requested/requisitioned individually.  They KF 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 UM/ Items with these codes are not to AVU; MLevel) be  requested/requisitioned MF-(Made at DS/ Individually.  They must be made AVUM Level) from  bulk  material  which  Is MH-(Made at GS Identified by the part number In the DESCRIPTION AND USABLE ON CODE (UOC) column and ML-(Made at Spe- listed in the Bulk Material group clalized Repairof the repair parts list in this Activity (SRA))RPSTL.  If the item is authorized MD- (Made atto you by the 3d position code of Depot) the SMR code, but the source code indicates it is made at a higher level, order the item from the higher level of maintenance. Items with these codes are not to be  requested/requisitioned AO-(Assembled by individually.  The parts that make UM/ AVUM up the assembled item must be Level) requisitioned or fabricated and AF-(Assembled by assembledatthe  level  of DS/AVIM maintenanceindicted by the Level) source code.  If the 3d position code  of  the  SMR   code GS Category authorizes you to replace the s egmy) item,  but  the  source  code AL-(Assembled by indicates the item is assembled SRA) at a higher level, order the item AD-(Assembled by from  the  higher  level  of Depot) maintenance. XA - Do not requisition an "XA"-coded item.  Or- der 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 a 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 mainte- nance. 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, re- place, 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  re- paired  and  identifies  the  lowest  maintenance  level  with the   capability   to   do   complete   repair   (i.e.,   perform   all authorized  repair  functions).    (NOTE:  Some  limited  re- pair   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: Code Application/Explanation O - Unit maintenance or aviation unit is the low-  est level that can do complete repair of the item. F - Direct support or aviation intermediate is the lowest level than can do complete repair of the item. 2