The backgound of my inquiry is: The business requires to statistically compare the customer order's confirmed delivery date/time against the Proof of Delivery date/time provided by e.g. the IDoc type DELVRY07.
There is a VL0n* delivery header tab "almost crying out for" this purpose named: Dates. (See the attached JPG file.) This view enables to maintain a planned begin date / time against actual occurencies. (The tab view is physically reprensented by several TSEG* tables.)
Having investigated the ECC 6.06 repository and SAP's Service Portal / OSS I came to the conclusion that this feature -- as well as the analogous VT0n* shipment tab "Further Dates" -- is a pure interactively maintainable data base,not updatable by means of exits or the like.
(Compare SAP note 351654 on "Time segment" saying. "There is general uncertainty or even confusion over how this should be achieved, since the delivered documentation is not sufficiently detailed.")
Looking forward to your opinions or even advice!