Definition: This field may be specified by the orderer, in which case it indicates the earliest date/time at which the services should be started. In many cases, however, the start date time will be implied or will be defined by other fields in the order record (e.g., urgency - STAT). In such a case, this field will be empty.
The filling service will often record a value in this field after receipt of the order, however, and compute an end time on the basis of the start date/time for the filling services internal use.