What PO update triggers an update to last_update_date on po_distributions_all?

Summary:

When one of the PO Line is updated for a specific PO, having multiple lines via a change order in the UI, the LAST_UPDATE_DATE is updated with the current date in the PO_DISTRIBUTIONS_ALL table for all active lines in the respective PO.

Content (please ensure you mask any confidential information):

It is seen that LAST_UPDATE_DATE is being updated on all lines on a PO in PO_DISTRIBUTIONS_ALL table when users have NOT touched other lines in the UI. The last_update_date on po_lines_all is only updated on the line that was updated via UI. Testing confirmed that last_update_date was updated on all lines of a PO in po_distributions_all as a result of a simple change to one line (an amount field (price/qty)) though no other lines were updated.