vastlint

VAST XML validation rules reference

Every rule vastlint enforces against the IAB VAST specification (versions 2.0 through 4.3) is documented here. There are currently 118 rules across 10 categories. Click any rule ID for a detailed explanation, spec reference, and a code example showing the fix.

error: ad will likely fail to render. warning: spec violation or risky practice. info: advisory.

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Required VAST fields (51)

errorVAST-2.0-root-elementRoot element must be <VAST>errorVAST-2.0-root-version<VAST> must have a version attributewarningVAST-2.0-root-version-valueVAST version attribute must be a recognised version stringerrorVAST-2.0-root-has-ad-or-error<VAST> must contain at least one <Ad> or <Error>warningVAST-4.0-wrapper-root-error<VAST> root contains both <Ad> and <Error> elements (invalid per VAST 4.0)errorVAST-2.0-ad-has-inline-or-wrapperEach <Ad> must contain exactly one <InLine> or <Wrapper>errorVAST-2.0-inline-adsystem<InLine> must contain <AdSystem>errorVAST-2.0-inline-adtitle<InLine> must contain <AdTitle>errorVAST-2.0-inline-impression<InLine> must contain at least one <Impression>errorVAST-2.0-inline-creatives<InLine> must contain <Creatives> with at least one <Creative>errorVAST-4.1-adservingid-present<InLine> must contain <AdServingId> (VAST 4.1+)errorVAST-4.0-universaladid-present<Creative> must contain <UniversalAdId> (VAST 4.0+)errorVAST-4.0-universaladid-idregistry<UniversalAdId> must have an idRegistry attributeerrorVAST-2.0-linear-duration<Linear> must contain <Duration>errorVAST-2.0-linear-mediafiles<Linear> must contain <MediaFiles> with at least one <MediaFile>errorVAST-2.0-mediafile-delivery<MediaFile> must have a delivery attributeerrorVAST-2.0-mediafile-type<MediaFile> must have a type attributeerrorVAST-2.0-mediafile-dimensions<MediaFile> must have width and height attributeserrorVAST-2.0-wrapper-adsystem<Wrapper> must contain <AdSystem>errorVAST-2.0-wrapper-impression<Wrapper> must contain at least one <Impression>errorVAST-2.0-wrapper-vastadtaguri<Wrapper> must contain <VASTAdTagURI>errorVAST-2.0-companion-resource<Companion> must contain at least one StaticResource, IFrameResource, or HTMLResourceerrorVAST-2.0-nonlinear-resourceInLine <NonLinear> must contain at least one StaticResource, IFrameResource, or HTMLResourceerrorVAST-3.0-pricing-model<Pricing> missing required model attributeerrorVAST-3.0-pricing-currency<Pricing> missing required currency attributewarningVAST-3.0-pricing-model-case<Pricing> model value should be lowercase in VAST 3.0 (cpm/cpc/cpe/cpv)warningVAST-3.0-pricing-currency-format<Pricing> currency attribute must be a 3-letter ISO-4217 codeerrorVAST-3.0-icon-program<Icon> missing required program attributeerrorVAST-3.0-icon-width<Icon> missing required width attributeerrorVAST-3.0-icon-height<Icon> missing required height attributeerrorVAST-3.0-icon-xposition<Icon> missing required xPosition attributeerrorVAST-3.0-icon-yposition<Icon> missing required yPosition attributeerrorVAST-3.0-icon-resource<Icon> must have at least one resource elementerrorVAST-4.0-category-authority<Category> missing required authority attributeerrorVAST-4.0-companion-clicktracking-id<CompanionClickTracking> missing required id attributeerrorVAST-4.0-universaladid-idvalue<UniversalAdId> missing required idValue attribute (VAST 4.0)warningVAST-4.1-universaladid-idvalue-removed<UniversalAdId> idValue attribute was removed in VAST 4.1errorVAST-4.1-universaladid-content<UniversalAdId> must have text content in VAST 4.1+errorVAST-4.1-mezzanine-delivery<Mezzanine> missing required delivery attributeerrorVAST-4.1-mezzanine-type<Mezzanine> missing required type attributeerrorVAST-4.1-mezzanine-width<Mezzanine> missing required width attributeerrorVAST-4.1-mezzanine-height<Mezzanine> missing required height attributewarningVAST-4.1-verification-no-resource<Verification> should have JavaScriptResource or ExecutableResourcewarningVAST-4.1-blockedadcategories-no-authority<BlockedAdCategories> should have authority attributewarningVAST-4.0-interactive-creative-no-api<InteractiveCreativeFile> should have an apiFramework attributewarningVAST-4.1-interactive-creative-type<InteractiveCreativeFile> should have a type attribute identifying the MIME typeerrorVAST-4.1-verification-vendor<Verification> is missing required vendor attributeerrorVAST-4.1-js-resource-apiframework<JavaScriptResource> is missing required apiFramework attributewarningVAST-4.3-js-resource-browser-optional<JavaScriptResource> should have a browserOptional attributeerrorVAST-4.1-exec-resource-apiframework<ExecutableResource> is missing required apiFramework attributeerrorVAST-4.1-exec-resource-type<ExecutableResource> is missing required type attribute

VAST document structure (2)

errorVAST-2.0-wrapper-depthWrapper chain depth exceeds the configured maximumwarningVAST-2.0-ad-sequenceMixed use of sequence attribute across <Ad> elements in a pod

VAST XML schema rules (22)

errorVAST-2.0-text-only-elementText-only element contains a child elementwarningVAST-2.0-unknown-attributeElement has an attribute not defined in the VAST specerrorVAST-2.0-inline-unknown-child<InLine> contains an unrecognised child elementerrorVAST-2.0-wrapper-unknown-child<Wrapper> contains an unrecognised child elementerrorVAST-2.0-creatives-unknown-child<Creatives> may only contain <Creative> elementserrorVAST-2.0-creative-unknown-child<Creative> contains an unrecognised child elementerrorVAST-2.0-linear-unknown-child<Linear> contains an unrecognised child elementerrorVAST-2.0-trackingevents-unknown-child<TrackingEvents> may only contain <Tracking> elementserrorVAST-2.0-mediafiles-unknown-child<MediaFiles> contains an unrecognised child elementerrorVAST-2.0-extensions-unknown-child<Extensions> may only contain <Extension> elementserrorVAST-2.0-videoclicks-unknown-child<VideoClicks> contains an unrecognised child elementerrorVAST-2.0-nonlinearads-unknown-child<NonLinearAds> contains an unrecognised child elementerrorVAST-2.0-nonlinear-unknown-child<NonLinear> contains an unrecognised child elementerrorVAST-2.0-companionads-unknown-child<CompanionAds> may only contain <Companion> elementserrorVAST-2.0-companion-unknown-child<Companion> contains an unrecognised child elementerrorVAST-3.0-icons-unknown-child<Icons> may only contain <Icon> elementserrorVAST-3.0-icon-unknown-child<Icon> contains an unrecognised child elementerrorVAST-3.0-iconclicks-unknown-child<IconClicks> contains an unrecognised child elementerrorVAST-2.0-creativeextensions-unknown-child<CreativeExtensions> may only contain <CreativeExtension> elementserrorVAST-4.2-closedcaptionfiles-unknown-child<ClosedCaptionFiles> may only contain <ClosedCaptionFile> elementswarningVAST-2.0-extension-misplaced-element<Extension> contains an element that has a dedicated location in the VAST specwarningVAST-2.0-creative-extension-misplaced-element<CreativeExtension> contains an element that has a dedicated location in the VAST spec

Value format rules (12)

errorVAST-2.0-duration-format<Duration> value does not match HH:MM:SS[.mmm] formaterrorVAST-2.0-mediafile-delivery-enum<MediaFile> delivery must be "progressive" or "streaming"warningVAST-3.0-skipoffset-formatLinear skipoffset does not match HH:MM:SS[.mmm] or n% formatwarningVAST-3.0-progress-offset-formatTracking progress offset does not match required formatwarningVAST-3.0-skip-event-no-skipoffsetskip tracking event present but Linear has no skipoffset attributeerrorVAST-3.0-minmaxbitrate-pair<MediaFile> must have both minBitrate and maxBitrate or neitherwarningVAST-3.0-bitrate-conflict<MediaFile> has both bitrate and minBitrate/maxBitratewarningVAST-4.0-tracking-event-removedfullscreen/exitFullscreen tracking events were removed in VAST 4.0errorVAST-4.1-tracking-event-valueTracking event attribute not in the valid set for this VAST versionwarningVAST-4.1-adtype-valueAd adType must be video, audio, or hybridwarningVAST-4.1-companion-renderingmode-valueCompanion renderingMode must be default, end-card, or concurrentwarningVAST-3.0-companion-required-attr<CompanionAds> required attribute must be all, any, or none

Security and URL rules (4)

infoVAST-2.0-mediafile-https<MediaFile> URL uses HTTP instead of HTTPSinfoVAST-2.0-tracking-httpsTracking or click URL uses HTTP instead of HTTPSerrorVAST-2.0-url-emptyURL field is emptywarningVAST-2.0-url-invalidURL field does not appear to be a valid URI

Consistency and parse rules (3)

errorVAST-2.0-parse-errorXML parse error — document may be malformedwarningVAST-2.0-version-mismatchDeclared version does not match structural signalswarningVAST-2.0-duplicate-impressionDuplicate <Impression> URL within the same <Ad>

Deprecated VAST features (5)

warningVAST-4.0-conditionaladconditionalAd attribute is deprecated as of VAST 4.1warningVAST-4.1-survey-deprecated<Survey> is deprecated as of VAST 4.1warningVAST-4.1-vpaid-apiframeworkapiFramework="VPAID" is deprecated as of VAST 4.1infoVAST-4.0-mediafile-apiframework<MediaFile apiFramework> is deprecated in VAST 4.0+ — use <InteractiveCreativeFile>warningVAST-2.0-flash-mediafileFlash-based MediaFile type is no longer supported

Ambiguous and underspecified rules (7)

errorVAST-3.0-progress-offset<Tracking event="progress"> requires an offset attributewarningVAST-3.0-icon-attrsIcon missing recommended attributes (program/width/height/position)warningVAST-2.0-nonlinear-dimensions<NonLinear> missing required width or height attributeswarningVAST-2.0-companion-dimensions<Companion> missing width or heightwarningVAST-4.0-wrapper-clickthrough<ClickThrough> inside Wrapper <VideoClicks> was removed in VAST 4.0 (re-allowed in 4.2)warningVAST-4.2-icon-fallback-image-width-height<IconClickFallbackImage> should have width and height attributeswarningVAST-2.0-linear-tracking-quartiles<Linear> has no standard quartile tracking events — measurement system receives no signal

CTV and SSAI-specific rules (3)

infoVAST-4.1-mezzanine-recommended<MediaFiles> has no <Mezzanine> — may be rejected in CTV/SSAI contextswarningVAST-4.1-vpaid-in-interactive-contextVPAID MediaFile alongside InteractiveCreativeFile — VPAID unsupported in CTVwarningVAST-4.1-ad-serving-id-empty<AdServingId> is present but empty

SIMID (9)

errorSIMID-1.0-simid-type-required<InteractiveCreativeFile apiFramework="SIMID"> must have type="text/html"errorSIMID-1.0-simid-url-empty<InteractiveCreativeFile apiFramework="SIMID"> must contain a non-empty URLerrorSIMID-1.0-simid-url-https<InteractiveCreativeFile apiFramework="SIMID"> URL must use HTTPSwarningSIMID-1.0-simid-variable-duration-valuevariableDuration must be "true" when present on a SIMID InteractiveCreativeFileerrorSIMID-1.0-simid-mediafile-requiredLinear SIMID ad must include a video/audio <MediaFile> alongside the interactive creativeerrorSIMID-1.1-nonlinear-simid-no-iframe<NonLinear apiFramework="SIMID"> must contain an <IFrameResource>warningSIMID-1.1-iframe-simid-type-required<IFrameResource> in SIMID <NonLinear> should have type="text/html"errorSIMID-1.1-iframe-simid-url-empty<IFrameResource> in SIMID <NonLinear> must contain a non-empty URLerrorSIMID-1.1-iframe-simid-url-https<IFrameResource> in SIMID <NonLinear> URL must use HTTPS