Not sure if this is a bug or something yet to be implemented so I've posted it here support.
When you are editing a query with existing operations and you change the display from standard to custom the operations are retained.
GREAT!
However when editing a reference list on a BO form and you change the display from Table of Items to Custom, then the existing operations are removed (not carried over) and they have to be keyed in again.
Cheers Rod