VAST-4.0-category-authority-not-uri
<Category> authority attribute is not a valid authority URL
Short answer
The authority attribute names the organization that maintains the category taxonomy, as a URL or bare domain (e.g. iabtechlab.com). A value that cannot be read as one (spaces, no domain, empty) means players and verification vendors cannot resolve the taxonomy the category codes belong to.
Why this matters in production
This rule is a strong risk signal. Tags with this issue often still parse, but they become brittle across SDKs, SSAI resolvers, and CTV environments. 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="my taxonomy">IAB1-1</Category>Valid
<Category authority="iabtechlab.com">IAB1-1</Category>VAST-4.0-category-authority-not-uri and other issues instantly.Open the VAST tag validator →