VAST-2.0-duration-format
<Duration> value does not match HH:MM:SS[.mmm] format
Short answer
VAST requires duration values to follow the HH:MM:SS or HH:MM:SS.mmm format. Plain English values like "30 seconds" or bare numbers like "30" are not valid and will cause players to fail to parse the duration.
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. Value-format rules tend to fail at the moment a player interprets a field such as duration, skipoffset, bitrate, or versioning. They are especially painful because the XML can look valid at a glance. Affected scope: VAST 2.0 and later (all versions).
How to fix
Rewrite the duration in HH:MM:SS format, e.g. 00:00:30 for 30 seconds or 00:01:30 for 90 seconds. Optionally append milliseconds: 00:00:30.500.
Invalid
<Duration>thirty seconds</Duration>Valid
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