PO details in PER_ALL_ASSIGNMENT_M table

Summary:

The table PER_ALL_ASSIGNMENT_M has Purchase order - PO_HEADER_ID and PO_LINE_ID fields in it. But at assignment page these fields are not available. Checked in HCM Design Studio but there too these fields are not available. So how to populate these fields?

Content (required):

We would like to tag  Purchase order - PO_HEADER_ID and PO_LINE_ID for contingent worker, so that it is easier to check their PO details. The seeded table - PER_ALL_ASSIGNMENT_M has these two fields, but it is not available in front end. So if these fields are available at assignment table, these fields should be there in the page else how can we populate the data? Anyone knows how these two fields can be populated.