TM 10-3930-222-24P 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) made from bulk material which MH (Made at GS is identified by the part number Level) in the DESCRIPTION AND USABLE ON  CODE  (UOC) ML (Made at Spe- column and listed in the Bulk cialized Repair   Material group of the repair Activity (SRA))    parts list in this RPSTL.  If the MD (Made at item is authorized to you by the Depot) 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 UM/AVUM make up the assembled item Level) must be requisitioned or AF (Assembled by   fabricated and assembledat the DS/AVIM level of maintenance indicated Level) source code.  If the 3d position AH (Assembled by   by the code of  the SMR code GS Category) authorizes you to replace the 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.  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 (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