When you allocate inventory to sales order lines in Business Central, you can control how that allocation behaves when stock is short. The assignment flexibility field on the sales order line lets you mark a line as either soft assignment or locked assignment. Soft assignment can be cleared and reassigned automatically when you run the assigned quantity report. Locked assignment is protected, so the system keeps that quantity reserved for the customer even when it reallocates everything else.
This gives you a practical way to prioritise important customers. If you have promised stock to a specific customer, you lock that line. The next time the system redistributes available inventory, it deletes all soft assignments and reassigns them in order of sales order number, but it leaves the locked lines untouched.
How assignment flexibility defaults to soft assignment
When you enter a quantity on a sales order line, the assignment flexibility is set to soft assignment by default. This only happens if there is available stock to cover the quantity. In the example, a sales order line dated May 10 needs 32 pieces, but there is no available stock in this scenario. Because of that, the system cannot set the assignment flexibility automatically. Had there been available inventory, the line would have been set to soft assignment.
Reading the graphical inventory profile
The graphical inventory profile shows demand and supply over time for the item. In this case there is a sizeable backlog with many demands that are not fulfilled. Looking only at the quantity already assigned, the inventory does not drop below zero, which means the assigned quantities are still covered by stock.
Around the period in May, the assignments are visible day by day. On April 25 there are 12 pieces assigned on one order. On May 1 there are 8 pieces assigned. On May 6 another 8 pieces are assigned, and that brings the inventory down to zero. So the existing demand already consumes the available stock up to that point.
Locking an assignment for an important customer
If a particular customer matters more than the others, you can manually set the assignment flexibility to locked assignment on that line. The assignment flexibility field itself is an information field used for filtering, so changing it does not by itself reserve the stock. You also enter the quantity manually, in this case the full 32 pieces, and you can lock the flexibility on other sales order lines in the same way.
Once you override the assignment manually, the inventory profile shows a problem. With the locked 32 pieces added on top of the existing demand, the inventory now goes to minus 32. That is expected at this stage, because you have manually forced the quantity onto the line before redistributing the rest.
Reassigning quantities while respecting locked lines
To resolve the situation, you run the assigned quantity report. This reassigns quantities across the sales order lines. The report deletes all soft assignments and then reassigns the available stock in order of appearance, meaning by sales order number. The locked assignment is respected and kept in place throughout this process. That is the key distinction between the two parameters on the sales order line.
After running the report, the important customer still has the full 32 pieces assigned. In the graphical profile, including the quantity assigned on the sales order line, the inventory no longer drops below zero. The older order from April 25 stays assigned, but the next two orders end up with nothing, because the locked line has taken those quantities.
When to lock and when to leave a line soft
Use locked assignment when you have made a firm promise to a customer and need to guarantee that stock stays reserved for them. Leave lines as soft assignment when they were just entered and you have not promised anything yet. Soft lines can then be freely reallocated the next time you reassign quantities.
Q&A
What is the default assignment flexibility on a sales order line in Business Central?
When you enter a quantity on a sales order line, the assignment flexibility defaults to soft assignment, provided there is available stock to cover the quantity. If no stock is available, the system cannot set it automatically.
What is the difference between soft assignment and locked assignment?
Soft assignment can be deleted and reassigned automatically when you run the assigned quantity report. Locked assignment is protected and kept in place during reassignment, so the reserved quantity stays with that customer.
How do I prioritise an important customer for limited stock?
Set the assignment flexibility on that customer’s sales order line to locked assignment and enter the quantity manually. When you run the assigned quantity report, the system deletes all soft assignments and reassigns stock by sales order number, but it respects the locked line so the customer keeps the quantity.
Does the assignment flexibility field reserve stock by itself?
No. The assignment flexibility field is an information field used for filtering and to control behaviour during reassignment. To force a quantity onto a line you also enter the quantity manually.
What happens to the inventory profile when I lock a quantity manually?
After manually overriding the assigned quantity, the inventory profile may show a negative value, such as minus 32, because the locked quantity is added on top of existing demand. Running the assigned quantity report then redistributes the soft assignments and brings the profile back in balance while keeping the locked line.