In regards to the SWII IID, the Message Function 4 is for pre-arrival changes whereas the Message Function 52 is for post arrival, pre-release changes.

Message Function 4 (Change)

All non-key fields can be changed (key fields that cannot be changed are: Business Number, Transaction ID and SO)

Message Function 52 (Amend)

Amend
All non-key fields can be changed (key fields that cannot be changed are: Business Number, Transaction ID and SO)

Adjust
Business Number, Transaction Number