Delivery modifier
A budget-weight object across supply segments. It allocates spend. It does not scale the bid the way a bid modifier does.
A delivery modifier weights how budget is allocated across matching supply segments. Terms carry targeting, rank, and weight, plus a required fallback weight. It is the budget-allocation sibling of a bid modifier, which scales price on a match.
Use the distinction. Bidding a placement down keeps you in the auction at a lower price. Weighting delivery tries to send more or less daily budget toward a segment. Neither is a hard exclude. Bid-downs reach Adprime Zero buyers only as proposals from the conversion optimizer; weighting delivery is not a buyer workflow today. Research on the exchange accounts we checked found the object documented and unused (zero delivery-modifier objects).
Do not ask an agent to "set a delivery modifier" as if it were a create_targeting call. If you need weighted allocation across deals or exchanges, that is still trader work.
For a first test, isolate one cell and read waste grain. Weights on a single remnant cell will not fix a mixed landing page.