the fields “Modified by/ Created by/ Modified date and time/ Created date and time” are basic information for tracking the data. they should be mandantory for all tables, especially for the PO tables “Purchase line versions/ Purchase order header versions/ Purchase orders /Purchase order lines”. but now the PO line table do not has Modified by column, and Purchase line versions table do not has "Modified by/ Created by/ Modified date and time/ Created date and time" columns. it is not easy to check who create and modified them.