The Temporary tab is shown in the Search Form, if the CDT is opened from the Register Customer Order or the Register Manufacturing Order procedures. You cannot change anything under this tab since the information is based on the order row, part number, period and quantity in the abovementioned registration procedures. Otherwise, you will get the same information as you get under the Own tab, but you cannot enter any validity period for the part.
Please note that these reservations only exist while the window is open. When you close the window, the reservations will be deleted. Also note that after saving a customer order with a delivery period, you should create a manufacturing order from the Register Customer Order procedure, that will replace the reservations from the CDT.