open-standards/wai/REGISTRY.md

WAI registry

The registry is the set of strings SPEC §5 registers, with the classes the specification gives each one. Its source of truth is one table in the reference implementation, wai-rs/src/codecs/registry.rs together with the class functions of wai-rs/src/codecs/mod.rs. wai registry export writes it out in machine-readable form:

file	what
registry/capabilities.json	every registered string with its kind, status, media class, role, fidelity tier, licence class, replicate class, set membership, registering section, edition and registration date; the named identifiers that are not capabilities; the unregistered labels
registry/capabilities.schema.json	JSON Schema (2020-12) for that file; its enums are the label sets below
vocab/v2.ttl, vocab/v2.jsonld, vocab/v2.shapes.ttl	the same registry as RDF, a JSON-LD context for manifests, and a SHACL shape that checks a manifest's capability and fallback against it, only the form of its media, and its parameter-set pins (vocab/README.md); a violation for a string the registry does not hold means the string is not registered in this revision, not that the envelope fails to conform or cannot be dispatched (SPEC §4, §8)
the table at the end of this file	the same registry, for reading

A library test (codecs::registry::tests::registry_export_matches_committed) and a CI step (wai registry export --check in .github/workflows/wai-conformance.yml) fail when a committed file differs from what the table renders. Edit the table, never the exported files.

Kinds

Every registered string has one kind.

• payload — a capability whose payload a sink decodes: it may be a WAI1 capability or fallback, or a WAI2 rendition.
• companion — a companion-only capability (SPEC §5, §7.1): its payload is applied with a base rendition and never on its own, so it is only ever a WAI2 companion.
• derivation — an operation of ISO/IEC 23001-16 (wai.derive.*, derived-tracks). It acts on samples another capability decoded and names no payload format.
• record — a signed record a WAI tool emits and verifies (a receipt kind: wai.asset.provenance, the quantum-operations receipts, the delivery records wai.video.manifest and its siblings). It names no payload format.

A derivation or record string is not a payload capability, so it is not dispatchable (SPEC §4): dispatch never takes an envelope's capability that names one, and step 5 may still take a usable fallback.

Two further tables hold strings that look like capabilities and are not:

• identifiers name a part of a capability's definition (wai.det.fixed64, the fixed-point floor; wai.world.sim.*, the simulation steps of the feed and avatar capabilities);
• unregistered labels are strings the reference implementation uses as labels that no revision registers, each with the reason.

Status

• registered — the payload format (for a record or derivation, the definition) is pinned.
• candidate — the string is registered but no revision has pinned its payload format. An encoder MUST NOT emit a candidate, and a sink MUST treat it as unsupported (SPEC §5, Candidate capabilities). The reference implementation lists candidates in codecs::is_candidate, reports an envelope that names one from Wai::check_candidates and WaiMulti::check_candidates, and never dispatches or selects one.

Every dispatch and selection function uses one predicate, codecs::is_dispatchable(cap), SPEC §4's dispatchable: false for a companion-only capability, a candidate, a record and a derivation; true for a registered payload capability that is not a candidate, and for a string this revision does not register, which a later MINOR revision may register (SPEC §8) and which a sink decodes only if it advertises it. A new dispatch or selection function MUST use it too.

Editions

A registration that names an edition of its standard carries that edition. A registration that names none carries the edition of its named standard current on the date it was registered, and no later edition or amendment: a later edition or amendment that changes the bitstream gets a capability string of its own (SPEC §8, Editions). The export records both: edition (a designation, or null for the edition current on the registration date) and registered (the date of the first commit of this repository that registers the string; the specification entered the repository on 2026-06-12, so a string registered before then carries that date).

Licence classes

Every payload and companion capability carries a licence class: royalty-free, patent-pool, proprietary or non-commercial (codecs::capability_license). It is a property of the capability, not a per-file claim. The classification has no default: a capability registered without a class is a registry defect the tests reject. The sources and residual caveats for each class are in research/media-codec-registry.md. A capability whose royalty status is not established is classified conservatively (patent-pool), never royalty-free; a candidate's class is provisional until a revision pins its payload format, since the licensing of a format not yet chosen cannot be established. Every derivation operation carries the class codecs::derivation::derivation_license gives it; a record carries none.

How to register a string

1. Add the capability constant to wai-rs/src/codecs/mod.rs and, for a payload or companion capability, list it in known_capabilities() and give it an arm in capability_tier, capability_license and capability_replicate_class (each function has no default, and the tests reject a registered capability without one). A record goes in RECORDS, a derivation in codecs::derivation.
2. Give it a row in ROWS of wai-rs/src/codecs/registry.rs: the SPEC §5 heading it is registered under, the edition it carries, and the registration date. A string whose payload format is not yet pinned also goes in CANDIDATES.
3. Register it in SPEC §5, under that heading, with its payload format and role. The test spec_and_registry_name_the_same_strings holds SPEC and the table to the same set of strings, in both directions.
4. Run cargo run --no-default-features --bin wai -- registry export from wai/wai-rs, and commit the files it writes.
5. Link it from the codec glossary entry that describes its bitstream, or list it in the glossary's GLOSSARY_NO_ENTRY table with the reason (glossary/SCHEMA.md).
6. Add a CHANGELOG entry.

Changing what a registered string carries is governed by SPEC §8: a payload format and a role are fixed once registered.

The registry

string	kind	status	media	role	licence	replicate	sets	registered in
wai.asset.provenance	record	registered	—	—	—	—	—	§5 Interactive, temporal & computed content
wai.audio.aac	payload	registered	audio	standalone	patent-pool	standard-unclassified	—	§5 Broadcast and streaming codecs
wai.audio.ac4	payload	registered	audio	standalone	proprietary	standard-unclassified	—	§5 Immersive audio, cinema, volumetric, haptics, HDR
wai.audio.avs3	payload	registered	audio	standalone	patent-pool	standard-unclassified	—	§5 Broadcast and streaming codecs
wai.audio.flac	payload	registered	audio	standalone	royalty-free	standard-defined	floor	§5 Mandatory floor
wai.audio.iamf	payload	registered	audio	standalone	royalty-free	standard-tolerance	—	§5 Immersive audio, cinema, volumetric, haptics, HDR
wai.audio.int_codec	payload	registered	audio	standalone	royalty-free	neural-int-exact	—	§5 Interactive, temporal & computed content
wai.audio.ivas	payload	registered	audio	standalone	patent-pool	standard-tolerance	—	§5 Immersive audio, cinema, volumetric, haptics, HDR
wai.audio.mpegh	payload	registered	audio	standalone	patent-pool	standard-unclassified	—	§5 Broadcast and streaming codecs
wai.audio.opus	payload	registered	audio	standalone	royalty-free	standard-tolerance	recommended	§5 Recommended modern set
wai.audio.scene	payload	registered	audio	standalone	royalty-free	standard-defined	—	§5 Interactive, temporal & computed content
wai.audio.score	payload	registered	audio	standalone	royalty-free	standard-defined	—	§5 Interactive, temporal & computed content
wai.avatar.pose	payload	registered	interactive	standalone	royalty-free	standard-defined	—	§5 Interactive, temporal & computed content
wai.derive.crop	derivation	registered	—	—	patent-pool	—	—	§5 Prior artifacts, general tensors and derivation operations
wai.derive.dissolve	derivation	registered	—	—	patent-pool	—	—	§5 Prior artifacts, general tensors and derivation operations
wai.derive.grid_composition	derivation	registered	—	—	patent-pool	—	—	§5 Prior artifacts, general tensors and derivation operations
wai.derive.identity	derivation	registered	—	—	patent-pool	—	—	§5 Prior artifacts, general tensors and derivation operations
wai.derive.mirror	derivation	registered	—	—	patent-pool	—	—	§5 Prior artifacts, general tensors and derivation operations
wai.derive.overlay_composition	derivation	registered	—	—	patent-pool	—	—	§5 Prior artifacts, general tensors and derivation operations
wai.derive.roi_selection	derivation	registered	—	—	patent-pool	—	—	§5 Prior artifacts, general tensors and derivation operations
wai.derive.rotation	derivation	registered	—	—	patent-pool	—	—	§5 Prior artifacts, general tensors and derivation operations
wai.derive.scaling	derivation	registered	—	—	patent-pool	—	—	§5 Prior artifacts, general tensors and derivation operations
wai.derive.srgb_fill	derivation	registered	—	—	patent-pool	—	—	§5 Prior artifacts, general tensors and derivation operations
wai.feed.state	payload	registered	interactive	standalone	royalty-free	standard-defined	—	§5 Interactive, temporal & computed content
wai.film.linear	payload	registered	video	standalone	royalty-free	standard-defined	—	§5 Interactive, temporal & computed content
wai.film.reel	payload	registered	video	standalone	royalty-free	standard-defined	—	§5 Interactive, temporal & computed content
wai.generate.spectral	payload	registered	image	standalone	royalty-free	generative-exact	—	§5 Neural capabilities
wai.haptic.mihs	payload	registered	haptic	standalone	patent-pool	standard-unclassified	—	§5 Immersive audio, cinema, volumetric, haptics, HDR
wai.haptic.signal	payload	registered	haptic	standalone	royalty-free	standard-defined	—	§5 Interactive, temporal & computed content
wai.image.avif	payload	registered	image	standalone	royalty-free	standard-tolerance	recommended	§5 Recommended modern set
wai.image.jp2	payload	registered	image	standalone	royalty-free	standard-tolerance	—	§5 Immersive audio, cinema, volumetric, haptics, HDR
wai.image.jpeg	payload	registered	image	standalone	royalty-free	standard-tolerance	recommended	§5 Recommended modern set
wai.image.jpegai	payload	registered	image	standalone	royalty-free	neural-entropy-exact	—	§5 Neural capabilities
wai.image.jxl	payload	registered	image	standalone	royalty-free	standard-tolerance	recommended	§5 Recommended modern set
wai.image.png	payload	registered	image	standalone	royalty-free	standard-defined	floor	§5 Mandatory floor
wai.mesh.draco	payload	registered	volumetric	standalone	royalty-free	standard-unclassified	—	§5 Immersive audio, cinema, volumetric, haptics, HDR
wai.mesh.glb	payload	registered	volumetric	standalone	royalty-free	standard-unclassified	—	§5 Interactive, temporal & computed content
wai.meta.dovi	companion	registered	metadata	companion	proprietary	standard-unclassified	—	§5 Immersive audio, cinema, volumetric, haptics, HDR
wai.meta.hdr10plus	companion	registered	metadata	companion	royalty-free	standard-unclassified	—	§5 Immersive audio, cinema, volumetric, haptics, HDR
wai.neural.bmshj2018	payload	registered	image	standalone	royalty-free	neural-float	—	§5 Neural capabilities
wai.neural.cmic	payload	registered	image	standalone	royalty-free	neural-float	—	§5 Neural capabilities
wai.neural.dac	payload	registered	audio	standalone	royalty-free	neural-float	—	§5 Neural capabilities
wai.neural.dcvc_fm	payload	registered	video	standalone	royalty-free	neural-float	—	§5 Neural capabilities
wai.neural.dcvc_rt	payload	registered	video	standalone	royalty-free	neural-float	—	§5 Neural capabilities
wai.neural.elic	payload	registered	image	standalone	royalty-free	neural-float	—	§5 Neural capabilities
wai.neural.encodec32	payload	registered	audio	standalone	royalty-free	neural-float	—	§5 Neural capabilities
wai.neural.glc	payload	registered	image	standalone	royalty-free	neural-float	—	§5 Neural capabilities
wai.neural.int_hyper	payload	registered	image	standalone	royalty-free	neural-int-exact	—	§5 Neural capabilities
wai.neural.int_mlicpp	payload	registered	image	standalone	royalty-free	neural-int-exact	—	§5 Neural capabilities
wai.neural.int_synth	payload	registered	image	standalone	royalty-free	neural-int-exact	—	§5 Neural capabilities
wai.neural.mbt2018_mean	payload	registered	image	standalone	royalty-free	neural-float	—	§5 Neural capabilities
wai.neural.mimi	payload	registered	audio	standalone	royalty-free	neural-float	—	§5 Neural capabilities
wai.neural.mlicpp	payload	registered	image	standalone	royalty-free	neural-float	—	§5 Neural capabilities
wai.neural.mlicv2	payload	registered	image	standalone	royalty-free	neural-float	—	§5 Neural capabilities
wai.neural.snac	payload	registered	audio	standalone	royalty-free	neural-float	—	§5 Neural capabilities
wai.neural.video_bmshj2018	payload	registered	video	standalone	royalty-free	neural-float	—	§5 Neural capabilities
wai.neural.wavtokenizer	payload	registered	audio	standalone	royalty-free	neural-float	—	§5 Neural capabilities
wai.pc.gpcc	payload	registered	volumetric	standalone	patent-pool	standard-unclassified	—	§5 Immersive audio, cinema, volumetric, haptics, HDR
wai.pc.vpcc	payload	registered	volumetric	standalone	patent-pool	standard-unclassified	—	§5 Immersive audio, cinema, volumetric, haptics, HDR
wai.prior.nnc	payload	registered	binary	standalone	patent-pool	standard-unclassified	—	§5 Prior artifacts, general tensors and derivation operations
wai.prior.set	payload	registered	binary	standalone	royalty-free	standard-defined	—	§5 Prior artifacts, general tensors and derivation operations
wai.quantum.calibration	record	registered	—	—	—	—	—	§5 Interactive, temporal & computed content
wai.quantum.circuit	payload	registered	binary	standalone	royalty-free	standard-defined	—	§5 Interactive, temporal & computed content
wai.quantum.job	record	registered	—	—	—	—	—	§5 Interactive, temporal & computed content
wai.semantic.clip	payload	registered	image	standalone	royalty-free	behavioral	—	§5 Neural capabilities
wai.semantic.perco2	payload	registered	image	standalone	non-commercial	behavioral	—	§5 Neural capabilities
wai.splat.4d	payload	registered	volumetric	standalone	royalty-free	standard-defined	—	§5 Interactive, temporal & computed content
wai.splat.int_codec	payload	registered	volumetric	standalone	royalty-free	neural-int-exact	—	§5 Interactive, temporal & computed content
wai.splat.sog	payload	candidate	volumetric	standalone	patent-pool	standard-unclassified	—	§5 Immersive audio, cinema, volumetric, haptics, HDR
wai.splat.spz	payload	registered	volumetric	standalone	royalty-free	standard-unclassified	—	§5 Interactive, temporal & computed content
wai.tensor.nnc	payload	candidate	binary	standalone	patent-pool	standard-unclassified	—	§5 Prior artifacts, general tensors and derivation operations
wai.ternary.tt	payload	registered	binary	standalone	royalty-free	standard-defined	—	§5 Interactive, temporal & computed content
wai.text.xz	payload	registered	text	standalone	royalty-free	standard-defined	recommended	§5 Recommended modern set
wai.text.zstd	payload	registered	text	standalone	royalty-free	standard-defined	floor	§5 Mandatory floor
wai.video.av1	payload	registered	video	standalone	royalty-free	standard-tolerance	recommended	§5 Recommended modern set
wai.video.av1.lossless	payload	registered	video	standalone	royalty-free	standard-tolerance	recommended	§5 Recommended modern set
wai.video.av2	payload	registered	video	standalone	royalty-free	standard-tolerance	—	§5 Broadcast and streaming codecs
wai.video.avc	payload	registered	video	standalone	patent-pool	standard-defined	—	§5 Broadcast and streaming codecs
wai.video.avs3	payload	registered	video	standalone	patent-pool	standard-unclassified	—	§5 Broadcast and streaming codecs
wai.video.channel	record	registered	—	—	—	—	—	§5 Neural capabilities
wai.video.evc	payload	registered	video	standalone	patent-pool	standard-unclassified	—	§5 Broadcast and streaming codecs
wai.video.evc.baseline	payload	registered	video	standalone	royalty-free	standard-unclassified	—	§5 Broadcast and streaming codecs
wai.video.hevc	payload	registered	video	standalone	patent-pool	standard-defined	—	§5 Broadcast and streaming codecs
wai.video.int_hyper	payload	registered	video	standalone	royalty-free	neural-int-exact	—	§5 Neural capabilities
wai.video.int_motion	payload	registered	video	standalone	royalty-free	standard-defined	—	§5 Neural capabilities
wai.video.j2k	payload	registered	video	standalone	royalty-free	standard-tolerance	—	§5 Immersive audio, cinema, volumetric, haptics, HDR
wai.video.keys	record	registered	—	—	—	—	—	§5 Neural capabilities
wai.video.lcevc	companion	registered	video	enhancement	patent-pool	standard-unclassified	—	§5 Broadcast and streaming codecs
wai.video.manifest	record	registered	—	—	—	—	—	§5 Neural capabilities
wai.video.package	record	registered	—	—	—	—	—	§5 Neural capabilities
wai.video.ssai	record	registered	—	—	—	—	—	§5 Neural capabilities
wai.video.vp9	payload	registered	video	standalone	royalty-free	standard-defined	—	§5 Broadcast and streaming codecs
wai.video.vvc	payload	registered	video	standalone	patent-pool	standard-defined	—	§5 Broadcast and streaming codecs
wai.world.live	payload	registered	interactive	standalone	royalty-free	standard-defined	—	§5 Interactive, temporal & computed content
wai.world.model	payload	registered	interactive	standalone	royalty-free	standard-defined	—	§5 Interactive, temporal & computed content
wai.world.replay	payload	registered	interactive	standalone	royalty-free	standard-defined	—	§5 Interactive, temporal & computed content
wai.world.scene	payload	registered	interactive	standalone	royalty-free	standard-defined	—	§5 Interactive, temporal & computed content

identifier (not a capability)	meaning	in
wai.det.fixed64	the fixed-point arithmetic floor the deterministic *-equivalence criteria are computed in	§5 Interactive, temporal & computed content
wai.world.sim.feed0	the identity simulation step of wai.feed.state	§5 Interactive, temporal & computed content
wai.world.sim.skeletal0	the skeletal-pose simulation step of wai.avatar.pose	§5 Interactive, temporal & computed content

unregistered label	reason
wai.quantum.mitigate	a receipt-kind label the wai-quantum crate seals; no revision of SPEC or of an extension registers it, so it is not a registered record
wai.quantum.decode	a receipt-kind label the wai-quantum crate seals; no revision of SPEC or of an extension registers it, so it is not a registered record
wai.quantum.compile	a receipt-kind label the wai-quantum crate seals; no revision of SPEC or of an extension registers it, so it is not a registered record
wai.quantum.rearrange	a receipt-kind label the wai-quantum crate seals; no revision of SPEC or of an extension registers it, so it is not a registered record
wai.quantum.qbom	a receipt-kind label the wai-quantum crate seals; no revision of SPEC or of an extension registers it, so it is not a registered record