R12 Purchasing: Requisitions can be locked by other users

Before reading My Oracle Support article "Line #### Of Requisition ### Currently Locked By Another User When Attempting Autocreate a Purchase Order." from note ID 1998470.1 I did not know that requisitions could be locked by other users except when there were true database locks going on in the system!  Check out the reasons behind this, and how it could have been prevented!