record  during  the  update.  The  final  line  of  each  entry Effects  the  updated  stock  record  after  all  transactions have  been  posted.  The  Transactions  Ledger  should  be maintained  on  file  for  approximately  1  year,  or  longer at the discretion of the supply officer. Transaction Error Listing The Transaction Error Listing contains transactions that  could  not  be  processed  because  of  errors. Transactions  appearing  on  the  listing  must  be  corrected and reinput since they do not appear on the Transaction Ledger and the computer maintains no record of them. The  Transaction  Error  Listing  represents  an  important part of the ship’s audit trail and should be maintained on  file  for  approximately  the  same  time  period  as  the Transaction  Ledger. Suspended  Transaction  Listing The   Suspended   Transaction   Listing   contains transactions that do not have invalid fields or data elements, but that could not be processed because of certain  conditions  that  exist  in  the  stock  records.  The suspended  transaction  will  appear  on  the  Suspended Transaction Listing for a maximum of 15 updates. If the  conditions  are  not  corrected  within  the  15-update period,  the  transaction  is  deleted  from  the  Suspended Transaction Listing and appears on the Transaction Error Listing. This listing should be retained for the same time period as the two previously discussed. Information Listing The Information Listing contains transactions that should  be  reviewed.  In  certain  situations  action  may  be required.  It  is  also  used  as  a  management  aid  in  that transactions worthy of the attention of the supply officer are flagged. Transaction Error Message Key Number Summary Report This report consists of  transactions by DI and Mark Number  (MKNR)  that  could  not  be  processed  because of  error(s).  From  this  report,  the  supply  officer  can determine  what  errors  are  being  made  and  the  possible causes. Master Stock Status and Locator Listing The  Master  Stock  Status  and  Locator  Listing (MSSLL)  is  a  periodic  printout  of  certain  essential  data elements  from  each  stock  record  in  the  MRF.  A supplemental  MSSLL  is  produced  automatically  after each   update   (except   when   processing   with   the FASTRAND drum) and contains current data on all stock numbers affected sines the last complete MSSLL was  produced. SYSTEM  OPERATION As stated, master files in the U-1500 system are maintained  on  magnetic  tape  and  are  kept  current through a daily, weekly, or monthly updating. This updating  is  a  commercial-type  processing  in  that  data from input transactions (on cards, tapes, or scanners) are processed sequentially against records in a master file. These records are changed or updated by the applicable transaction and a new master file is created. Processing (or updating) is done on an exception basis in that any transaction  or  record  that  contains  a  detectable  error  is rejected from processing and is output to a printed error listing  and/or  an  error  card.  No  note  is  made  of acceptable  records  that  are  processed.  Within  the system,  inputs  are  called  transitions,  and  each  contains a  three-character  document  identifier  (DI)  that identifies  a  particular  type  of  transaction;  e.g.,  a requisition,  a  receipt,  or  an  issue.  The  computer  is programed to recognize these DIs and to process the transaction  against  the  proper  stock  and  financial records. All inputs or outputs in the system use the standard   MILSTRIP/MILSTRAP   document identifiers,  where  applicable. ISSUES Issues are made on the DD Form 1348 instead of the NAVSUP Form 1250-1 discussed previously. A DD Form  1348m  prepared  for  use  as  an  internal  issue document  is  shown  in  figure  11-4.  The  same information must be shown on the DD Form 1348 as is required  on  the  NAVSUP  Form  1250-1  although preprinted blocks are not provided for this purpose. The data element titles in blocks L, M, N, P, R, and U of the DD Form 1348m in figure 11-5 have been placed on the form  for  easier  identification. The DD Form 1348 is processed much in the same manner as the NAVSUP Form 1250-1. They are first checked  by  SSC  personnel  to  make  sure  that  the mandatory data elements are present and legible for the type   of   action   to   be   taken   (e.g.,   issue,   or   DTO procurement).  In  addition,  SSC  personnel  must  make sure that the mandatory 3-M data elements described and shown in figure 11-4 are present when applicable. Write the location of the material on the back of the 11-7