Flattened Bid Requests
Flattened Bid Requests help third-party bidders make smarter decisions and understand what types of creatives are eligible on bid requests. By flattening bid requests, the publisher's queries are separated into distinct individual bid requests to make it easier for third-party bidders to understand and bid on RTB inventory. For detailed developer documentation, see the Authorized Buyers Real-Time Bidding (RTB) Protocol.
Instances where you would flatten bid requests:
Video ad breaks
If you want to correlate the individual bid requests together to a unique publisher query for offline analysis or bidding, pay attention to the field google_query_id in Google Protocol or OpenRTB extensions. This will be the same across all flattened requests: