Placement modifier
A percentage that raises your bid for one placement. Effective bid = base × (1 + modifier).
The lever for balancing performance across placements. The goal is roughly equal ACOS everywhere, with spend concentrated where conversion is strongest.
AutoPPC only proposes modifier changes from realized campaign × placement × day evidence. Search-term placement breadcrumbs are not a substitute for the report, and a modifier moved on inferred data is a guess wearing a number.
One lever per campaign per run: bid and modifier never move together, because you would not be able to tell which one worked.