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feat(schema): revisit VAST 4.4 support for AdCP 3.3 #7247
Description
Context
PR #7230 proposed adding 4.4 to the VAST version enum. We are deferring that change from AdCP 3.2 because VAST 4.4 is not yet a published IAB Tech Lab specification:
- The VAST 4.4 document still says
Publication Date TBD. vast_4.4.xsdidentifies itself as a draft for working-group discussion.- The finalized CTV Ad Portfolio signaling guidance uses
version="4.2"in its concrete examples. - The draft XSD has an unresolved content-model/cardinality issue: VAST 4.4: xs:choice minOccurs=0 maxOccurs=unbounded on vastInLine_type / vastWrapper_type drops all child cardinality InteractiveAdvertisingBureau/VAST#58.
There is early test activity, including VAST 4.4 fixtures and validator demos, but we have not found independent adopter evidence that AdCP currently blocks a real integration.
Revisit for 3.3
Add VAST 4.4 when either:
- IAB Tech Lab publishes the final VAST 4.4 specification/schema, or
- An independent adopter needs truthful
version="4.4"declarations for a concrete interoperability test and can describe the compatibility expectations.
When revisiting, start from #7230 and revalidate the enum, tracker event/version gates, documentation examples, and changeset against the then-current IAB artifacts.
Activity
aleksUIX commentedon Sep 4, 2026
Follow-up on the IAB side of this: InteractiveAdvertisingBureau/vast#59 now has in-tree xmllint fixtures for the three #58 cases (empty InLine, empty Wrapper, repeated AdSystem). Still waiting on IAB to land the schema fix.
bokelley commentedon Sep 21, 2026
Manual triage outcome
Classification: dependency-blocked standards/schema follow-up.
Current status: AdCP still intentionally advertises VAST 2.0–4.3. The source enum and CTV guidance explicitly exclude 4.4. Upstream IAB issue
VAST#58remains open, and its schema-fix PRVAST#59is also open and unmerged. There is still no concrete adopter-blocking case here.Decision: route to Spec Backlog, not committed 3.3 scope. The issue is worth preserving, but a numbered release cannot promise an unpublished external standard.
Next gate: either IAB publishes the final VAST 4.4 specification/schema, or an independent adopter supplies a concrete interoperability requirement. At that point, revive the #7230 change set and revalidate enum, tracker gates, examples, and conformance against the final artifact.