A complete file update using 2 tables

This is a complete update program using the balance-line method. However, to save repetition, it uses the copy statement to copy record definitions into the text. These copy statements would be expanded by the Cobol compiler. Cope does not attempt to expand them itself.

(You can scroll the text area below.)

* Let's assume that we have stored the following master file
      * record definition as the source library text 'Account' ...

1   Account.
           2   Account-No          pic x(8).
               88  At-End          value high-values.
           2   Name                pic x(20).
           2   Balance             pic s9(8)v99.

* ... and the following record definitions as 'Updates' ...

1   Insertion.
           2   Account-No          pic x(8).
               88  At-End          value high-values.
           2   filler              pic x.
               88  Is-Insertion    value "+".
           2   Name                pic x(20).
       1   Deletion.
           2   filler              pic x(8).
               88  Is-Deletion     value "-".
           2   filler              pic x.
       1   Deposit.
           2   filler              pic x(8).
           2   filler              pic x.
               88  Is-Deposit      value ">".
           2   Credit              pic 9(6)v99.
       1   Withdrawal.
           2   filler              pic x(8).
           2   filler              pic x.
               88  Is-Withdrawal   value "<".
           2   Debit               pic 9(6)v99.

* ... so we can then COPY them as required.

IDENTIFICATION DIVISION.
       Program-ID.                 Sequential-Update.

ENVIRONMENT DIVISION.
       Input-Output Section.
       File-Control.
           select optional Old-Master assign to "backup",
               organization is indexed,
               record key is Account-No of Old-Master,
               access is sequential.
           select New-Master assign to "master",
               organization is indexed,
               record key is Account-No of New-Master,
               access is sequential.
           select Unsorted-Updates assign to "trans",
               organization is sequential.
           select Updates assign to "temp2",
               organization is sequential.
           select Work-File assign to "temp1".

DATA DIVISION.
       File Section.
       FD  Old-Master.
           copy Account.
       FD  New-Master.
           copy Account.
       FD  Unsorted-Updates.
           copy Updates.
       FD  Updates.
           copy Updates.
       SD  Work-File.
           copy Updates.

Working-Storage Section.
       77  Current-Account         pic x(8).
           88  At-End              value high-values.
       77  Account-Status          pic 9.
           88  Account-Missing     value 0.
           88  Account-Exists      value 1.

PROCEDURE DIVISION.
      *    The following examples show most of Cope's features.
      *    Notice that an action can usefully be an IF statement.
      *Update-Accounts.
      *    Note table to update an accounts file.
      *    1 2 2 2 3 3  group.
      *    x - - - - -  sort Work-File on ascending Account-No of
      *                     Work-File, with duplicates in order
      *                     using Unsorted-Updates giving Updates.
      *    x - - - - -  open input Old-Master, Updates
      *                     output New-Master.
      *    - y n n - -  is At-End in Current-Account.
      *    - - y n - -  is Account-No of Old-Master = Current-Account.
      *    - - x - - -  move Account in Old-Master
      *                     to Account in New-Master.
      *    - - 1 2 - -  set Account-.. to true. Exists Missing.
      *    - - - - y n  is Account-No of Updates = Current-Account.
      *    - - - - x -  perform Apply-Update thru Apply-Update-Exit.
      *    1 - 1 - - -  read .., at end set At-End of .. to true.
      *                     Old-Master.
      *    1 - - - 1 -  ,,  Updates.
      *    - - - - - x  if Account-Exists write Account in New-Master,
      *                 invalid key display "Fatal Error",
      *                 STOP RUN.
      *    x - - - - x  if Account-No of Updates
      *                         < Account-No of Old-Master
      *                 move Account-No of Updates to Current-Account
      *                 else move Account-No of Old-Master
      *                     to Current-Account.
      *    - x - - - -  close Old-Master Updates New-Master.
      *    - x - - - -  stop run.
      *    2 - 3 3 3 2  next group.
      *
      *    Note.
      *    Group 2 is executed once for each Account-No.
      *    On entry to Group 2, the following conditions apply -
      *    * Both input files are in Account-No order.  If there are
      *      multiple updates for an account, they are in input order.
      *    * Current-Account is the smaller of the two Account-nos in
      *      Updates and Old-Master.
      *    * All active Accounts with keys less than Current-Account
      *      have been updated and written to New-Master.
      *    * Either the input areas contain unprocessed records, or they
      *      contain a high-valued Account-No.
      *
      *    Group 3 is executed once for each update.
      *    On entry to Group 3, the following conditions apply -
      *    * If Account-Exists is true, the New-Master record area
      *      contains a record, otherwise the account is inactive.
      *    * The New-Master record area is up to date for all updates
      *      except the one currently in the input record area.
      *    * The Updates record area contains an unprocessed record or a
      *      high-valued Account-No.
      *    * The Old-Master record area contains an unprocessed record
      *      or a high-valued Account-No.
      *
      *Apply-Update.
      *    Note table to update the New-Master record area.
      *    1 1 2 2 3 3 4 4  is Is-.. in Updates.
      *                     Insertion, Deletion, Deposit, Withdrawal.
      *    y n y n y n y n  is Account-Exists.
      *    - 1 - - - - - -  move .. of Updates to .. of New-Master.
      *                     Account-No.    ,, Name.
      *    - 1 2 - - - - -  set Account-.. to true. Exists, Missing.
      *    - - - - x - - -  add Credit of Updates
      *                         to Balance of New-Master.
      *    - - - - - - x -  subtract Debit of Updates
      *                         from Balance of New-Master.
      *    1 - - 2 - 3 - 4  display "Error: Account ",
      *                         Current-Account,
      *                         " .., .. ignored.".
      *                     exists,    missing,  missing, missing;
      *                     insertion, deletion, deposit, withdrawal.
      *
      *    Note that insertions and deletions change the Account-Status.

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