VMAP-1.0-adsource-content
`<AdSource>` must contain exactly one of `<VASTAdData>`, `<AdTagURI>`, or `<CustomAdData>`
Short answer
Each <AdSource> must contain exactly one ad-delivery child: <VASTAdData> (embedded VAST), <AdTagURI> (redirect to a VAST URL), or <CustomAdData> (proprietary format). Zero or more than one is invalid.
Why this matters in production
This rule is usually a delivery blocker. Many players, SDKs, and ad servers will discard the response or skip the affected creative once this condition is hit. VMAP rules validate the ad break schedule envelope. Malformed break timing, wrong namespace declarations, or invalid AdSource content prevent players from resolving any of the ads in the playlist. Affected scope: VMAP 1.0 (all VMAP documents).
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