TM 5-2410-234-20P (1) Source Code.  The source code tells you how to get an item needed for maintenance, repair, or overhaul of an end item/equipment.  Explanations of source codes follows: Code Application/Explanation Stocked  items;  use  the  applicable  NSN  to request/requisition  items  with  these  source codes.  They are authorized to the category indicated   by   the   code   entered   in   the   3d position of the SMR code. **Items coded PC are subject to deterioration. Items    with    these    codes    are    not    to    be requested/requisitioned   individually.      They are  part  of  a  kit  which  is  authorized  to  the maintenance   category   indicated   in   the   3d position of the SMR code.  The complete kit must be requisitioned and applied. Items  with  these  codes  are  not  to be requested/requisitioned individually.      They   must   be   made from bulk material which is identified   by   the   part   number      in the    DESCRIPTION  AND  USABLE ON CODE (UOC) column and listed in   the   Bulk   Material   group   of   the repair parts list in this RPSTL. If  the  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 individually.    The  parts   that   make up   the   assembled   item   must   be requisitioned or fabricated and assembled at the level of maintenance indicated by the source   code.      If   the   3d   position code  of  the  SMR  code  authorizes you   to   replace   the   item,   but   the source   code   indicates   the   item   is assembled  at  a  higher  level,  order the   item   from   the   higher   level   of maintenance. XA- Do not  requisition an "XA"-coded item.  Order its next higher assembly.  (Also, refer to the NOTE below.) XB- If  an  "XB"  item  is  not  available  from  salvage,  order  it using the FSCM 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    FSCM    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. (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- Intermediate Direct support or aviation intermediate   is   the   lowest   level   that   can   do complete repair of the item. H- Intermediate General support is the lowest level that can do complete repair of the item. 2 PA PB PC PD PE PF PG KD KF KB MO-(Made at UM/ AVUM Level MF-(Made at IDS/ AVUM Level MH-(Made at IGS Level) ML-(Made at Specialized Repair act (SRA)) MD-(Made at Depot) AO-(Assembled by UM/AVUM Level) AF-(Assembled by IGS Category AL-(Assembled by SRA) AD-(Assembled by Depot)