TM 5-3805-257-24P 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 AVUM Level) to be requested/requisitioned MF-(Made at DS/ Individually.  They must be AVUM Level) madefrom bulk material which is MH-(Made at GS identified by the part number in Level) the DESCRIPTION AND ML-(Made Spe-) USABLE ON CODE (UOC) cialized Repair column and listed in the Bulk Activity (SRA) Material group of the repair MD-(Made at parts list in this RPSTL.  If the Depot) item  is  authorized  to  you  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. Items  with  these  codes  are  not to be requested/requisitioned AO-(Assembled by individually.  The parts that UMI AVUM makeup the assembled item Level) must be requisitioned or AF-(Assembled by fabricated and assembled at the DSIAVIM level of maintenance indicted by Level) the source code.  If the 3d AH-(Assembled by position code of the SMR code GS  Category authorizes you to replace the AL-(Assembled by item, but the source code SRA) indicates the item is assembled AD-(Assembled by at a higher level, order the item Depot) from the higher level of maintenance. 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 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 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: Code Application/Explanation O - Unit  maintenance  or  aviation  unit  is  the  lowest 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