EWM - Reserved quantities in WT

"A product WT reserves the quantities, so that these are no longer available for other product WTs." An HU-WT does not reserve quantities. Therefore it is possible with /SCWM/POST to change the stock type even when subsequent open or waiting WTs exist. Example (without QM / QIE):

1. GR comes into the receiving StType A as B5-Blocked in Putaway. As per the INB settings, two subsequent WTs are automatically generated; one for a transfer from StType A to StType B, and then the final putaway from B to C.

2. The stock in the HU at StType A is released (manually with /SCWM/POST) to F1-Unrestricted use in putaway.

3. The WT for transfer to from A to B is confirmed AND the system automatically updates the stock type in the final putaway WT to F1-Unrestricted use.

If you try this with a product WT (GR without an HU), it won't work. Because the reservation leaves no stock available for the posting. Error messages are:

- Posting change quantity reduced due to missing available quantity

- Could not find the source stock

What is the practical logic i.e. the reasoning behind this?

Thanks-!