Ann: Preliminary Final Report, page-63

Nothing unusual in the reporting of change in inventory. In simple terms this is partly offset by in part by raw materials(just the next line item).
As an example: if you buy a bolt for $10 that you plan to sell again, then your raw meterial cost would show -$10 and your inventory would be +$10. You haven't made a profit or loss yet as you haven't sold it.
Finished goods are valued at cost(parts, consumables plus labour). Inventory is just valued at cost. The change is very noticeable for RFT due to the size of the change in finished goods(not yet shipped) plus work in progress/inventory.