It would be nice to have the option of having multiple comment fields for SO and PO lines with an editable field title. Kind of like an additional attributes for each SO and PO line.
That way if company wants to track line item numbers they could have a comment filed for that. Need to make internal notes for a SO or PO lines you could have a comment field for that as well. Need to record due dates for individual SO lines that is possible to. Need to ship just the line complete? Have a checkbox for that.
The number of comment fields and titles could be set in the Reference Book settings. It would also be handy to have the ability to require the field or not. Also the ability to set the type of data allowed in the field, i.e. date, number, checkbox or list.
This would cover a lot of different use cases.