Field help (SDHNUM) 

The delivery number is used to identify the delivery in a unique fashion. This number is either assigned automatically or entered upon each delivery creation with respect to the setup of the Sequence number(s) associated to the chosen Delivery type.
If the delivery sequence number is set to automatic assignment then this field cannot be accessed and the number is assigned on creating the delivery.
Conversely, if the sequence number is set to manual assignment, the number can be entered manually. If it is not entered by the user, the system automatically assigns a delivery number according to the sequence number.

SEEINFO Notes: