Orders with direct association with Invoices should be
able to change the payment rule - but others not.
These include warehouse order (WP).
Payment Rule must be hidden here.
Logged In: YES
Updated Dictionary; Seems that OrderType is not
automatically loaded anymore - only when C_DocTypeTarget_ID
is changed (via Callout DocType).
** Fixed in R2.4 **
Column Order.PaymentRule - ReadOnly when @OrderType@='WP'
MField ReadOnly Evaluation & Load of Dependant Info