Discriminator identifying this as a VAST tracker asset. See /schemas/creative/asset-types for the registry.
The VAST tracking event this URL fires on. Maps 1:1 to the VAST Tracking event="..." attribute inside TrackingEvents. MUST NOT be impression (belongs in the VAST Impression element — model as a url asset with url_type: "tracker_pixel"), clickTracking / customClick (belong in VideoClicks), error (VAST Error element), or any of viewable / notViewable / viewUndetermined / measurableImpression / viewableImpression (children of the VAST ViewableImpression element, not TrackingEvents).
Optionalmacro_declarations?: [Exact tokens in url and their resolver/encoding contracts.
Optionaloffset?: stringVAST offset attribute. Required when vast_event is progress; ignored otherwise for compatibility with existing 3.x manifests. Format matches the VAST 4.2 XSD Tracking@offset pattern: HH:MM:SS or HH:MM:SS.mmm for absolute time (two-digit hours, minutes 00–59, seconds 00–59), or an integer percentage 0–100 suffixed with %. Negative offsets are NOT permitted — the VAST 4.2 XSD pattern does not allow a leading minus.
Optionaltarget?: "linear" | "non_linear" | "companion"Which VAST creative element this tracker scopes to — linear for <Linear>/<TrackingEvents>, non_linear for <NonLinearAds>/<TrackingEvents>, companion for <CompanionAds>/<Companion>/<TrackingEvents>. Defaults to linear. Existing 3.x assets remain structurally permissive; a tracker execution contract applies the standards-valid event/target matrix when matching a creative to a product.
Optionalprovenance?: Provenance
A single tracker URL bound to a VAST
TrackingEventsevent. Emitted by the creative agent as a decomposed VAST-event URL; the sales agent assembles these into the VASTTrackingEventsblock at serve time. IMPORTANT: this asset type is forTrackingEventsURLs only (start, quartiles, complete, pause, mute, etc.). TheImpressionURL MUST be modeled as aurlasset withurl_type: "tracker_pixel", not as a vast_tracker withvast_event: "impression". Decomposed trackers let format requirements bind specific measurement events (e.g., MRC viewable) without forcing the buyer to construct a full VAST tag.