TM   55-2835-208-23P (3)   Third. IdentiFy   the   item   on   the   Illustration   and   note   the   illus- tration   figure   and   Item   number   of   the   item. (4)   Fourth. Using   the   Repair   Parts   Listing,   find   the   figure   and   item number   notes   on   the   illustration. b. When  National  Stock  Number  or  Part  Number  is  Known: ( 1 )    F i r s t . Using   the   Index   of   National   Stock   Numbers   and   Part   Num- bers,  find  the  pertinent  National  stock  number  or  part  number. This   index   is   in NIIN   sequence   followed   by   a   list   of   part   numbers   in      alphameric   sequence,   cross- referenced  to  the  illustration  figure  number  and  item  number. (2)   Second. After  finding  the  figure  and  item  number,  locate  the  fig- ure  and  item  number  in  the  repair  parts  list. 6. Abbreviations. Abbreviations HSG ACCEL ALT AN APU ASSY AUX BOI BRG CCMPSR EA FIG ID IN LH MS NHA NIIN NSN P/N PR QTY RH SCD TURB U/M U/O U/W Explanation Acceleration Alternate Air   Force-Navy Auxiliary  Power  Unit Assembly Auxillary Basis   of   Issue Bearing Compressor Each Figure Housing Identification Inch Left-Hand Military   Specification Next Higher Number National   Item   Identification   Number National  Stock  Number Part  Number Pair Quantity Right-Hand Specification    Control    Draining Thick Turbine Unit  of  Measure Used-On Used  With THK 7