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The provided call stack consists of four files: AP300P.ocl36.txt, AP300P.rpg36.txt, AP300.ocl36.txt, and AP300.rpg36.txt. These files work together to implement an Accounts Payable (A/P) vendor file update process on the IBM System/36, specifically for clearing Month-to-Date (MTD) and Year-to-Date (YTD) totals in the vendor master file. Below, I’ll identify the use cases implemented by this program suite and then provide a function requirement document for a non-interactive version of the primary use case, focusing on business requirements and calculations.

Use Cases Implemented

The program suite implements a single primary use case with variations based on input parameters. The use case is:

  1. Clear Vendor MTD and YTD Totals:
  2. Description: Updates the A/P vendor master file by clearing MTD totals (discounts, purchases, payments) for selected vendors and, optionally, YTD totals (purchases, discounts, payments) while preserving last year’s data. The process includes validation of input parameters, sorting of vendor records, backup of the vendor file for IRS 1099 processing, and maintenance of a 12-month file history.
  3. Variations:
    • Company Selection: Process all non-deleted vendors (ALL) or specific companies (CO with up to three company numbers).
    • YTD Clearing: Clear YTD totals (KYYTDY = 'Y') or only MTD totals (KYYTDY = ' ').
    • Execution Mode: Run immediately or submit to a job queue (KYJOBQ = 'Y', 'N', or ' ').
  4. Components:
    • AP300P.ocl36.txt: Controls the overall job flow, invoking AP300P.rpg36.txt and conditionally AP300.ocl36.txt.
    • AP300P.rpg36.txt: Validates user inputs (company selection, YTD flag, year, job queue) via a screen interface.
    • AP300.ocl36.txt: Sorts the vendor file, creates backups, and invokes AP300.rpg36.txt.
    • AP300.rpg36.txt: Performs the actual MTD/YTD clearing in the vendor file.

No additional use cases are implemented, as the suite is focused solely on this update process with configurable options.

Function Requirement Document

The following document reimagines the primary use case as a non-interactive function that accepts inputs programmatically (instead of via a screen) and completes the A/P vendor file update process. The document is concise, focusing on business requirements and necessary calculations, and assumes a modern programming context while retaining the core logic from the System/36 programs.

Function Requirement Document: AP Vendor File Update

Overview

The APVendorUpdate function updates the Accounts Payable (A/P) vendor master file by clearing Month-to-Date (MTD) and optionally Year-to-Date (YTD) totals for selected vendors, ensuring data integrity and compliance with IRS 1099 requirements. It accepts input parameters programmatically, validates them, sorts vendor records, creates backups, and performs the updates.

Inputs

  • CompanySelection (string): "ALL" for all non-deleted vendors or "CO" for specific companies.
  • CompanyNumbers (array of strings, max 3): Company codes (2 bytes each) if CompanySelection = "CO". Empty if "ALL".
  • ClearYTD (boolean): true to clear YTD totals, false to clear only MTD totals.
  • Year (integer, 4 digits): Year for 1099 backup (required if ClearYTD = true, e.g., 2025).
  • JobQueue (boolean): true to queue the update, false to run immediately.
  • LibraryPrefix (string): Prefix for file names (e.g., "PROD" for PRODAPVEND).

Outputs

  • Status (string): "Success", "ValidationError", or "SystemError".
  • ErrorMessage (string): Description of validation or system errors, if any.
  • UpdatedRecords (integer): Number of vendor records updated.

Process Steps

  1. Validate Inputs:
  2. Ensure CompanySelection is "ALL" or "CO". Return "ValidationError" with message "Company selection must be 'ALL' or 'CO'" if invalid.
  3. If CompanySelection = "CO", verify CompanyNumbers contains 1–3 valid 2-byte company codes in the vendor file. Return "ValidationError" with message "Invalid company number" if any code is invalid or all are empty.
  4. If CompanySelection = "ALL", ensure CompanyNumbers is empty. Return "ValidationError" with message "Do not specify companies when selecting 'ALL'" if not empty.
  5. If ClearYTD = true, ensure Year is a valid 4-digit year (> 0). Return "ValidationError" with message "A 4-digit year is required when clearing YTD" if invalid.

  6. Ensure JobQueue is true or false. Return "ValidationError" with message "Job queue must be 'Y' or 'N'" if invalid.

  7. Check Exclusive Access:

  8. Verify no users are accessing the A/P system. Return "SystemError" with message "A/P system in use; ensure exclusive access" if locked.

  9. Sort Vendor Records:

  10. Filter the vendor master file (<LibraryPrefix>APVEND) to include only non-deleted records (DeletionFlag ≠ 'D').
  11. If CompanySelection = "CO", include only records matching CompanyNumbers.

  12. Sort by company (2 bytes) and vendor number (5 bytes) into a temporary file (<LibraryPrefix>AP300S).

  13. Create Backups for 1099 (if ClearYTD = true):

  14. Copy <LibraryPrefix>APVEND to:
    • APVN<Year> (e.g., APVN2025).
    • <LibraryPrefix>VN<Year> (e.g., PRODVN2025).

  15. Overwrite existing files and create if they don’t exist.

  16. Maintain 12-Month File History:

  17. Delete the oldest backup file (<LibraryPrefix>UCVEND) if it exists.
  18. Rename files to shift history:
    • <LibraryPrefix>UBVEND to <LibraryPrefix>UCVEND.
    • <LibraryPrefix>UAVEND to <LibraryPrefix>UBVEND.
    • ... down to <LibraryPrefix>U1VEND to <LibraryPrefix>U2VEND.

  19. Copy <LibraryPrefix>APVEND to <LibraryPrefix>U1VEND, overwriting if exists.

  20. Update Vendor Records:

  21. For each record in <LibraryPrefix>AP300S, update the corresponding record in <LibraryPrefix>APVEND:
    • MTD Updates (always):
    • Set MTDDiscounts to 0.
    • Set MTDPurchases to 0.
    • Set MTDPayments to 0.
    • Set PreviousBalance to CurrentBalance.
    • YTD Updates (if ClearYTD = true):
    • Move YTDPurchases to LastYearPurchases.
    • Move YTDPaid to LastYearPaid.
    • Set YTDPurchases to 0.
    • Set YTDDiscounts to 0.
    • Set YTDPaid to 0.

  22. Track the number of updated records.

  23. Execute or Queue:

  24. If JobQueue = true, submit the update process to a job queue.
  25. If JobQueue = false, execute immediately.
  26. Return "Success" with the count of updated records or "SystemError" with an error message if execution fails.

Business Rules

  1. Exclusive Access: The A/P system must not be in use during the update to prevent data corruption.
  2. Company Selection:
  3. "ALL" processes all non-deleted vendors.
  4. "CO" processes only specified, valid company codes (1–3).
  5. Invalid or conflicting company selections are rejected.
  6. MTD Clearing: Always clear MTD discounts, purchases, and payments, preserving the current balance as the previous balance.
  7. YTD Clearing:
  8. Clear YTD purchases, discounts, and payments only if ClearYTD = true.
  9. Preserve YTD data in last-year fields (LastYearPurchases, LastYearPaid) for auditing.
  10. Require a valid 4-digit year for 1099 backups.
  11. Backups for 1099: Save two copies of the vendor file (APVN<Year>, <LibraryPrefix>VN<Year>) before clearing YTD totals.
  12. File History: Maintain a rolling 12-month history of vendor file backups (<LibraryPrefix>U1VEND to <LibraryPrefix>UCVEND).
  13. Data Integrity:
  14. Process only non-deleted records.
  15. Preserve the current balance (CurrentBalance) during updates.
  16. Ensure backups are created before modifying the vendor file.

Calculations

  • MTD Updates:
  • MTDDiscounts = 0
  • MTDPurchases = 0
  • MTDPayments = 0
  • PreviousBalance = CurrentBalance
  • YTD Updates (if ClearYTD = true):
  • LastYearPurchases = YTDPurchases
  • LastYearPaid = YTDPaid
  • YTDPurchases = 0
  • YTDDiscounts = 0
  • YTDPaid = 0

Assumptions

  • The vendor master file (<LibraryPrefix>APVEND) contains fields for MTD/YTD totals, deletion flag, company, and vendor number.
  • The system supports file operations (copy, rename, delete) and job queuing.
  • Input validation ensures only valid data is processed, eliminating the need for interactive error correction.

Explanation

  • Use Case Identification: The suite implements one core use case—clearing MTD/YTD totals—with variations for company selection, YTD clearing, and execution mode. All components (AP300P.ocl36.txt, AP300P.rpg36.txt, AP300.ocl36.txt, AP300.rpg36.txt) contribute to this single process, with no additional use cases identified.
  • Function Requirement Document:
  • Non-Interactive Design: The document reimagines the process as a function that accepts inputs directly, bypassing the screen interface (AP300PS1 from AP300P.rpg36.txt).
  • Business Focus: Emphasizes business rules (e.g., exclusive access, company filtering, 1099 backups) and calculations derived from AP300.rpg36.txt (e.g., MTD/YTD field updates).
  • Integration: Incorporates logic from all four files:
    • Validation from AP300P.rpg36.txt (company selection, YTD flag, year).
    • Sorting and backups from AP300.ocl36.txt (#GSORT, CPYF).
    • Updates from AP300.rpg36.txt (MTD/YTD clearing).
    • Job control from AP300P.ocl36.txt (queue or immediate execution).
  • Conciseness: Streamlines the process into clear steps and rules, avoiding technical System/36 specifics (e.g., OCL syntax, RPG indicators) while preserving functionality.

This document provides a modernized, non-interactive specification for the A/P update process, suitable for implementation in a contemporary system while retaining the original business logic. If you need further refinements or additional details, let me know!