VAST Wrapper

A VAST Wrapper doesn't contain the ad creative — it contains a VASTAdTagURI pointing to another VAST document, which may itself be a wrapper pointing to yet another, chaining multiple ad servers together (common when an SSP passes a bid response back through an intermediary before reaching the final demand source). Each hop adds a round-trip request before the media file begins buffering, so CTV players enforce a maximum wrapper depth — typically 3 to 5 — and throw a VAST error 302 if the chain exceeds it.