VAST Extension type="pos" With a plcmt Child Still Validates. Stitchers Read type.

The VAST InLine extension, when improperly labeled, can cause issues in video ad campaigns. For instance, an extension type= pos with a plcmt child still validates despite its wrong attribute placement. The format reporting may show squeezeback geometry or nothing at all due to this issue. The integer 5, correct for Pause, must be correctly placed within the extension.

The child tag name should match the placement subtype. The 'type' attribute signals this block as a pos signal; if the inner tag does not match the declared signal, the block will be dropped. The IAB Tech Lab finalized CTV Ad Portfolio signaling in July 2026, and VAST side rounds trip four AdCOM enumerations inside the Extension ext= adcom node.

Each signal gets its own extension node, with the type attribute naming which signal the extension carries. The child element repeats the name and holds the integer value. This pattern exists because the VAST response outlives the bid request, and SSAI stitchers and measurement vendors often learn what was sold from the creative envelope.

Mislabeling at the wrapper can lead to a pause integer being inside a node advertised as geometry. The type attribute must match the payload element name for the portfolio guidance to work. Production consumers are not symmetric and treat type as the selector. If the declared AdCOM signal in type does not match the payload element name, the VAST-4.4-adcom-extension-type-mismatch rule flags this case.

The bug here is mislabeling at the wrapper, not the value-level mismatch. QA can catch this issue before traffic by using the VAST tag tester and VAST inspector. The type mismatch warning survives automation better than eyeballing four nearly identical extension blocks.