detailed description of each item and stock numbers of substitute  items.  It  also  includes  illustrations  and diagrams  of  many  types  of  material.  The  ASG  is  printed in six different sections. You still must use the ML-N to check for unit price, current NSN, and unit of issue. Consolidated Master Cross-Reference List The  Consolidated   Master   Cross-Reference   List (C-MCRL) is a consolidated list of all NSN items of supply in the FSC system. Consequently, it includes many  NSNs  that  are  not  listed  in  the  ML-N.  The C-MCRL is distributed annually to Navy users. The C-MCRL is made up of two parts. Part I crosses both reference  numbers  and  CAGE  numbers  to  NSNs.  Part II crosses NSNs to both reference numbers and CAGE numbers. DETERMINING STOCK LEVELS The determination of stock levels for individual items depends on whether the item is SIM or non-SIM. This section focuses on the manual SIM computation. SIM ITEM COMPUTATION OF DEMAND-QUARTERLY The demand quantities entered in the Issues column of  each  SIM  stock  record  during  the  past  6-month, 9-month, or 12-month period are totaled. Based upon the total quantity determined for the demand period, the high  limit,  low  limit,  and  safety  level  (HL/LL/SL) quantities in each SIM stock record will be adjusted, as necessary, to reflect the quantities authorized in the appropriate  average  endurance  table  as  illustrated  in figure  8-6.  Computation  of  the  total  demand  quantity will  be  more  frequent,  if  necessary,  to  reduce  the possibility of stock shortages or excesses. Periods of unusual demand will be excluded from the demand period. Quantities issued during an unusual demand period will be excluded from the computation of the total  demand  quantity.  In  determining  the  total  demand quantity,  inventory  and  survey  losses  of  missing material  will  be  included;  inventory  and  survey  losses of on-hand material unfit for either issues or transfers will not be included. When computing the total demand quantity in stock records that reflect a unit of issue change  such  as  PR  to  EA  or  EA  to  DZ,  any  issue quantities  posted  before  the  change  must  be  converted (in the count, not on the stock record) to quantities that correspond with the current unit of issue. The demand period  used,  the  total  demand  quantity  determined,  and the revised HL/LL/SL quantities should be made in pencil  because  of  the  frequent  changes  normally required. Assuming  a  prescribed  average  endurance  level  of 75 days and an order and shipping time (O&ST) of 30 days, the revised data entries in figure 8-6 should be used as  follows: If the total quantity issued from 18 April to 17 October 1993 (6 months) equals 20; then, for a 75-day average endurance and a 6-month demand period, figure 8-6 indicates 14 as the high limit, 10 as the low limit, and  7  as  the  safety  level.  When  the  quarterly computation  of  demand  results  in  a  total  demand quantity that is not listed in the average endurance table, the  appropriate  HL/LL/SL  quantities  can  be  determined by: l selecting two (or three, if necessary) of the listed demand  quantities  that,  when  combined,  equal  the  total demand  quantity  determined  from  the  stock  record;  and then l adding the HL/LL/SL quantities for each demand quantity  selected. For  example,  assuming  a  prescribed  average  endurance of  75  days,  an  authorized  O&ST  of  30  days,  and  a 6-month  demand  period,  the  HL/LL/SL  quantities authorized for a total demand quantity of 35 can be determined from the table as follows: Listed demand quantities HL  LL SL When the average endurance tables for 9-month and 12-month  demand  periods  are  used  for  determining  the HL/LL/SL  quantities  authorized,  a  quantity  of  one  for each additional 3-month period must be added to each of the totals derived by the method described in the above  computation.  Per  OPNAVINST  4441.12,  the range and depth of allowance material may be changed at the shipboard level under stockage criteria prescribed by  approved  shipboard  procedures.  Such  procedures  are authorized  by  fleet  commanders  in  chief  for  use  of variable  operating  and  safety  levels  and  for  intensive inventory management of special items. 8-13