I think the original post is asking if there is a way to add a memo to a sales order, so that memo is unique to that order. For example, MEMO - "SHIPPING, please make sure to include the catalog with this shipment.", then depending on forms used, display that message in a 'memo' box at the bottom of the pack list or order form. This would also be handy to record changes to the order, or other notes that may or may not need to be printed.
Bottom line is that I don't think MAS90 facilitates this feature. Maybe a good wish list item.