A frequent misunderstanding is the assumption that the unrestricted use stock is identical with available stock
Unrestricted use stock is a stock type, that can be used for everything, has no restriction based on its condition. Other stock types are quality stock and blocked stock.
Available stock can be equal, can even be more than unrestricted use stock, can be less than unrestricted use stock. You define yourself in the ATP checking rules how you calculate the available part of your stock
A look into our warehouse:
and the same in the stock overview transaction MMBE
You see 263 are in unrestricted use, 1 is in quality inspection.
But how much is available?
Depends on the point of view.
If you are a CSR and you want to check how much of this can be sold with the next order or if you are checking the stock/requirements list e.g. as a planner.
On the left you see transaction CO09 availability overview used by the CSR, on the right the Stock/Requirements list from the planner
Click the picture to enlarge, if you can’t read it
CO09 transaction shows 262 available, MD04 shows 264 available in the stock line on top. And both do not equal the 263 unrestricted use stock.
Why is this?
CO09 actually starts with 263, you can see this in Rec./reqd qty column, the ATP quantity got immediately reduced by the reservation of 1. And it did not include the quality inspection stock.
This is defined in OVZ9 Availability check control. The availability check 02 is coming from the material master, the 01 is my selected checking rule when executing CO09.
As you can see, safety stock is defined as available here, and on the right it is defined what is considered as incoming and outgoing movements.
Contrary MD04, the stock requirements list shows 264 as available, but why? Because Quality inspection stock is included into available stock by definition of Net requirements calculation.
Additionally you can define in customizing transaction OMI8 Available stocks if you include even stock in transfer, blocked stock and restricted use stock (this is a batch status)
Let us enter a purchase order of 20 and see how the situation develops.
Both transactions show the purchase order as MRP element, both numbers go up by 20.
CO09 shows now 282 and MD04 shows 283
Wait…CO09 shows as well 262, why 2 different ATP quantities in CO09?
Because CO09 shows a total at plant level, and it shows a total at storage location level (and it will have a total at batch level if the material is batch managed)
And since no storage location was entered in the purchase order, only the available stock at plant level goes up.
And why is a purchase order considered as available stock? See your checking rule for CO09, purchase orders are marked to be considered as incoming movement. And in MD04 it is considered too, the available stock goes up at the date when the goods are planned to be delivered.
Next experiment. I add a safety stock of 50 in the material master MRP2 view. What happens to CO09 and MD04?
As expected, based on the checking rule definition, CO09 does not change because safety stock is defined as available.
But MD04 got a new line showing the safety stock, and reduces this quantity from the available quantity.
One last activity, I add a sales order for 100
And in both transactions the sales order can be seen as a reduction from the available quantity…at plant level
It is not reduced from the storage location level, because the storage location was not entered in the sales order.
I hope this rough overview with these small examples helps you to know that unrestricted use stock is different from available stock.