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VAST-4.0-category-authority-unknown

VAST-4.0-category-authority-unknown

<Category> authority is not a recognised IAB Content Taxonomy authority

InfoValuesIAB Tech Lab Content TaxonomyVAST 4.0, 4.1, 4.2, and 4.3

Short answer

The authority value is a well-formed URL, but it is not one of the IAB Content Taxonomy registry hosts (iabtechlab.com and subdomains, iab.com). Custom taxonomies are legal per spec, but category codes under a private authority only work when every party in the delivery chain resolves it the same way.

Why this matters in production

This rule is advisory rather than fatal, but it still matters for portability, debugging speed, and keeping tags predictable across different buyers and playback stacks. 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 4.0, 4.1, 4.2, and 4.3.

Invalid

<Category authority="taxonomy.example.com">IAB1-1</Category>

Valid

<Category authority="https://www.iabtechlab.com/IABTC/2.2">IAB1-1</Category>
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Other Values rules

VAST-4.0-category-authority-not-uri<Category> authority attribute is not a valid authority URLVAST-4.1-blockedadcategories-authority-not-uri<BlockedAdCategories> authority attribute is not a valid authority URLVAST-4.1-blockedadcategories-authority-unknown<BlockedAdCategories> authority is not a recognised IAB Content Taxonomy authorityVAST-4.1-verification-vendor-format<Verification> vendor should use a domain-qualified identifier such as company.com-omidVAST-4.1-verification-tracking-reasonverificationNotExecuted tracking URI should include the [REASON] macroVAST-2.0-duration-format<Duration> value does not match HH:MM:SS[.mmm] formatVAST-2.0-mediafile-delivery-enum<MediaFile> delivery must be "progressive" or "streaming"VAST-3.0-skipoffset-formatLinear skipoffset does not match HH:MM:SS[.mmm] or n% format