What is the purpose of the Allocated field on the inventory maintenance Transaction Detail tab?

Question

 When and what updates the field Allocated in the Transaction Detail tab of inventory?

  

Answer

The field is populated when stock is received for back to back sales orders i.e. stock received for a back to back purchase order raised to fulfill back orders on a back to back sales order.

In the screen shot above, the last two lines are allocated.  The Order > On Back Order tab for the inventory item shows the source back to back sales order number (100479) and the linked back to back purchase order number (100508).  

Sales order 100498 is a normal sales order and stock can be allocated to that order in the usual way i.e. Process Back Order or Manual Back Order Release.

The only way Allocated stock can be freed up is to cancel the back orders on the back to back sales order.