Data Definition - Fields not available to add to def

Another problem I am having is that if you go to the Purchase Order
Release Tab, you will see that the table/field for the UofM's is
PORel.IUM & PORel.PUM. Then go to the Data Definition and try to find
these fields in the respective table - they are not listed. One would
assume that UofM's for inventory items for both the detail tab and
relaease tab of PO Entry would default in from a relation to the
Part.IUM and Part.PUM fields. Again, this is apparently not on the
agenda to fix in 8.0