How to write the where clause for a table-based value set, to extract the data based on the item num

Summary

How to write the where clause for a table-based value set, to extract the data based on the item number in the current object

Content

A DFF segment "Package String" is created under PO_ATTRIBUTE_VALUES, which is agreement additional line level.
The value set is expected to be a table based value set, which shall extract the list of value based on the item id at the current agreement line. For example, when the agreement line item is "500018", then the lov of that DFF should be all UOM conversion rates defined for that item.

The question is, how to identify the item number (or item id) in the where clause of the sql? We did try to use "