Creates the deal in real time and returns the Sovrn external deal ID (SVN_…) synchronously. Pass ?dryRun=true to run the full validation pipeline without creating anything. A request whose buyers include dv360 must also satisfy the DV360 field requirements (see the DV360 buyers section); violations return 400 naming the field. A pmp request whose buyers include thetradedesk needs schedule.endDate, before the same calendar date 2 years after schedule.startDate (see the Trade Desk buyers section). An open request may leave buyers out or send it empty: the deal gets a live deal ID that no buyer receives until a PATCH adds a DSP. A pmp request names at least one buyer.