Currently, reportEvent supports two “seller” destinations: seller and component-seller. The documentation does not define what these destinations refer to in a single-seller versus a multi-seller auction.

A naive guess might suppose that seller refers to only the top-level seller in a multi-seller auction and that component-seller does not refer to anyone in a single-seller auction.

Can we clarify whether this is indeed the case, and if not, add additional details to the documentation to clarify what these destinations mean?

If it is the case, then the current reportEvent API may be insufficient for buyers’ needs. This is because a buyer will likely need to report certain events to the “immediate” seller, meaning they would need to use seller as the destination if they won a single-seller auction, or component-seller if they won a multi-seller auction. This is problematic because the call to reportEvent will be triggered from within an ad, where there is no ability to determine what type of auction was run.
If the guess above is correct, then we propose two new seller destinations:

• top-level-seller: Refers to the only seller in a single-seller auction, or the top-level seller in a multi-seller auction.
• immediate-seller: Refers to the only seller in a single-seller auction, and the component seller in a multi-seller auction.