Web accessibility projection profile 0

Status: executable bounded research profile (nuif-web-accessibility-0). This profile projects portable NUIF semantics into inert native HTML and ARIA, then compares computed role, accessible name and supported state exposure across pinned Chromium, Firefox and WebKit test engines. It is not an arbitrary ARIA serializer, a behavior runtime or a claim about branded browsers and native platform accessibility APIs.

Portable subset

The profile accepts at most 4,096 structurally valid entities and 8,192 relationships. Ten roles are admitted:

• button, checkbox, radio and switch for the bounded interactive semantic surface;
• img, main, navigation, paragraph, region and group for bounded content and landmark semantics.

Native HTML is preferred where its implicit role matches: button, checkbox and radio input, main, nav, named section and p. switch, img and group use explicit roles because there is no equivalent element in this profile. Required-name, prohibited-name and role/state combinations are checked before output. switch requires an explicit Boolean checked state. A direct accessible name and a labelled-by relationship cannot both supply the same node’s name.

The Boolean state subset is deliberately role-specific:

• button: disabled, expanded, pressed;
• checkbox/radio: checked, disabled, required;
• switch: checked, disabled;
• non-widget roles: no state keys in profile 0.

Relationships map by stable entity identifier: labelled-by to aria-labelledby, described-by to aria-describedby, controls to aria-controls, owns to aria-owns and flow-to to aria-flowto. Repeated relationship targets and unnamed labelled-by targets fail closed. The source order of multiple relationship targets is retained because it can affect accessible-name computation. owns additionally requires a directed, acyclic, single-owner graph; multiple semantic parents and owned-tree cycles are rejected before HTML is emitted.

Direct and referenced names are normalized to the whitespace form produced by the accessible-name algorithm before they become oracle expectations. A name that is empty after normalization fails closed rather than silently becoming an unnamed control.

Security and behavior boundary

Output contains no scripts, external URLs, event handlers or generated application behavior. Native controls retain their built-in focus and state exposure, but the profile does not invent activation results, navigation or business logic. A correct accessibility tree is not evidence of keyboard-flow, interaction or application behavior equivalence.

Unsupported roles, states, ambiguous names, malformed containment and relationships outside the profile return typed errors without partial output. The projection keeps data-nuif-id on every element so a foreign observation can be attributed back to the stable NUIF entity.

Foreign oracle

cargo xtask gate-accessibility generates one eleven-node fixture covering every admitted role and Boolean state, installs the exact Playwright 1.62.1 browser set and compares the required role/name/state subset plus full ARIA snapshots across its Chromium, Firefox and WebKit engines. The report records package, engine, Node, operating-system and architecture versions. Required-subset mismatches are classified as semantic loss; non-required tree differences are retained separately as host-tree differences.

The current macOS/arm64 trial reports identical bounded snapshots from Chromium 151.0.7922.34, Firefox 153.0 and WebKit 26.5. Hosted Linux evidence is produced by CI and must not be inferred merely from workflow configuration.

Artifacts:

• target/accessibility-mapping-static-report.json;
• target/accessibility-mapping-report.json;
• target/accessibility-mapping-fixture.html;
• target/accessibility-mapping-expected.json.

Descriptions as direct semantic strings, numeric/value states, live regions, tables, trees, grids, composite-widget focus, keyboard interactions and native Apple/Microsoft/Linux/mobile mappings require separate model and profile work.

Canonical source.