Negative stock is a message, not a number to zero out.

I am the finance manager at an industrial distributor, closing September 2026. I have 4 files:
stock on hand at 31 Aug and 30 Sep, every stock movement in September, purchase order lines and sales order lines.
1. List every item with a negative quantity at 30 Sep.
2. For each one, trace its movements in date order from the 31 Aug quantity. Show the running balance
   and the first day it went below zero.
3. Explain in one line why it went negative. Quote the movement and the document (PO, sales order or return)
   that shows the cause. Check the PO lines for dock date, date received in the system, unit of measure and item code,
   and the sales order lines for the quantity ordered.
4. Group the items by cause.
Do not guess. If the files do not show the cause, say so.

Now fix the causes, not the numbers.
1. For each negative item, write the correction that fixes the cause: which document, what quantity, which item.
   Show the quantity after the fix and the value change at unit cost.
2. Say if the fix changes any other item.
3. Next to each, write the one question to ask and who to ask.
4. Compare 2 totals: the value change from fixing the causes, and the value change from
   one adjustment that sets every negative item to zero.

Here are the column names from my [SYSTEM NAME] exports.
Stock on hand: [PASTE THE HEADER ROW]. Stock movements: [PASTE]. PO lines: [PASTE]. Sales order lines: [PASTE].
Match each one to: item, unit of measure, unit cost, quantity at month start, quantity at month end,
movement date, movement type, quantity, document reference, dock date, date received in the system,
quantity ordered.
Tell me which ones are missing and what I would need to export to get them.
Do not guess a match. If unsure, ask.