Field help (STOFCYSIH) 

The shipment site can only be entered in the case of a direct invoice or credit memo with stock transaction.
It is initialized by the default site associated with the user and remains modifiable providing no line has been entered. The shipment site entered MUST be declared as a warehouse in the site table.
From this field, it is possible to directly enter a shipment site whose existence is controlled in the corresponding table or to use the contextual button or use the contextual button to select a shipping site in the table.