# References External standards and documentation cited by the checks in this bundle. * [A Guide to Sharing for Webmasters](a-guide-to-sharing-for-webmasters.md) - Meta * [A Well-Known URL for Changing Passwords](a-well-known-url-for-changing-passwords.md) - W3C Web Application Security Working Group * [A2A Protocol — Agent Discovery](a2a-protocol-agent-discovery.md) - A2A Project (Linux Foundation) * [A2A Protocol — Specification](a2a-protocol-specification.md) - A2A Project (Linux Foundation) * [a2aproject/A2A on GitHub](a2aproject-a2a-on-github.md) - A2A Project * [Accessibility Checker — Ambiguous Anchor Text](accessibility-checker-ambiguous-anchor-text.md) - Equalize Digital * [Accessibility Checker — Empty Button](accessibility-checker-empty-button.md) - Equalize Digital * [Accessibility Checker — Empty Link](accessibility-checker-empty-link.md) - Equalize Digital * [Accessibility Checker — Image Missing Alternative Text](accessibility-checker-image-missing-alternative-text.md) - Equalize Digital * [Accessibility Checker — Low Contrast](accessibility-checker-low-contrast.md) - Equalize Digital * [Accessibility Checker — Missing Form Label](accessibility-checker-missing-form-label.md) - Equalize Digital * [Accessibility Checker — Missing Language Declaration](accessibility-checker-missing-language-declaration.md) - Equalize Digital * [ActivityPub — W3C Recommendation](activitypub-w3c-recommendation.md) - W3C * [Agent Skills Discovery via Well-Known URIs (RFC draft)](agent-skills-discovery-via-well-known-uris-rfc-draft.md) - Cloudflare * [Agent Skills specification](agent-skills-specification.md) - agentskills.io * [Agentic Resource Discovery (ARD) specification](agentic-resource-discovery-ard-specification.md) - ARD Project (Linux Foundation) * [AI Catalog standard](ai-catalog-standard.md) - AI Catalog Working Group, Linux Foundation * [Allow passkey reuse across your sites with Related Origin Requests](allow-passkey-reuse-across-your-sites-with-related-origin-requests.md) - web.dev * [Announcing the Agentic Resource Discovery specification](announcing-the-agentic-resource-discovery-specification.md) - Google * [Anthropic — Crawlers](anthropic-crawlers.md) - Anthropic * [Anthropic — docs.anthropic.com Markdown source (live example)](anthropic-docs-anthropic-com-markdown-source-live-example.md) - Anthropic * [Apple — Allowing apps and websites to link to your content](apple-allowing-apps-and-websites-to-link-to-your-content.md) - Apple Developer Documentation * [Apple — Applebot-Extended](apple-applebot-extended.md) - Apple * [Apple — Supporting associated domains](apple-supporting-associated-domains.md) - Apple Developer Documentation * [ARIA Authoring Practices — Breadcrumb](aria-authoring-practices-breadcrumb.md) - W3C WAI * [ARIA Authoring Practices Guide — Read Me First](aria-authoring-practices-guide-read-me-first.md) - W3C WAI * [BCP 47 — Tags for Identifying Languages](bcp-47-tags-for-identifying-languages.md) - IETF * [Bing — IndexNow](bing-indexnow.md) - Bing * [Bing Webmaster — Robots meta tag](bing-webmaster-robots-meta-tag.md) - Bing * [Breadcrumb structured data](breadcrumb-structured-data.md) - Google Search Central * [Build and submit a sitemap](build-and-submit-a-sitemap.md) - Google Search Central * [California Attorney General — Frequently Asked Questions: CCPA](california-attorney-general-frequently-asked-questions-ccpa.md) - California Office of the Attorney General * [Chrome for Developers — Back/forward cache](chrome-for-developers-back-forward-cache.md) - Google * [Chrome for Developers — Break up long tasks with scheduler.yield()](chrome-for-developers-break-up-long-tasks-with-scheduler-yield.md) - Chrome for Developers * [Chrome for Developers — Cross-document view transitions](chrome-for-developers-cross-document-view-transitions.md) - Google * [Chrome for Developers — hidden=until-found and the beforematch event](chrome-for-developers-hidden-until-found-and-the-beforematch-event.md) - Google * [Chrome for Developers — Same-document view transitions](chrome-for-developers-same-document-view-transitions.md) - Google * [Chrome for Developers — Scroll-driven animations](chrome-for-developers-scroll-driven-animations.md) - Google * [Chrome for Developers — Speculation Rules](chrome-for-developers-speculation-rules.md) - Google * [Chrome Status — No-Vary-Search](chrome-status-no-vary-search.md) - Google * [Chrome User Experience Report](chrome-user-experience-report.md) - Chrome for Developers * [Chromium — IDN in Google Chrome](chromium-idn-in-google-chrome.md) - Chromium project * [Cloudflare — Forget IPs: using cryptography to verify bot and agent traffic](cloudflare-forget-ips-using-cryptography-to-verify-bot-and-agent-traffic.md) - Cloudflare * [CNIL — Cookies and other trackers](cnil-cookies-and-other-trackers.md) - CNIL * [CNIL — Use of Google Analytics and data transfers to the United States](cnil-use-of-google-analytics-and-data-transfers-to-the-united-states.md) - CNIL * [Colorado's approach to Universal Opt-Out requirements](colorado-s-approach-to-universal-opt-out-requirements.md) - IAPP * [Content Security Policy Level 3](content-security-policy-level-3.md) - W3C * [Cool URIs don't change](cool-uris-don-t-change.md) - W3C — Tim Berners-Lee * [CSS Color Adjustment Module Level 1 — the color-scheme property](css-color-adjustment-module-level-1-the-color-scheme-property.md) - W3C * [CSS Containment Module Level 2](css-containment-module-level-2.md) - W3C * [CSS Containment Module Level 2 — Using content-visibility: hidden](css-containment-module-level-2-using-content-visibility-hidden.md) - W3C * [CSS Device Adaptation Module — viewport meta](css-device-adaptation-module-viewport-meta.md) - W3C * [CSS Overflow Module Level 3 — scrollbar-gutter](css-overflow-module-level-3-scrollbar-gutter.md) - W3C CSSWG * [CSS Scroll-driven Animations Module Level 1](css-scroll-driven-animations-module-level-1.md) - W3C * [CSS Text Module Level 3 — Line Breaking and Word Boundaries](css-text-module-level-3-line-breaking-and-word-boundaries.md) - W3C * [CSS Values and Units Module Level 4 — Viewport-relative lengths](css-values-and-units-module-level-4-viewport-relative-lengths.md) - W3C CSSWG * [CSS View Transitions Module Level 2](css-view-transitions-module-level-2.md) - W3C * [CSS Writing Modes Level 3](css-writing-modes-level-3.md) - W3C * [Digital Asset Links protocol](digital-asset-links-protocol.md) - Google Developers * [Digital Asset Links — Verify Android App Links](digital-asset-links-verify-android-app-links.md) - Google Developers * [draft-ietf-httpbis-rfc6265bis — Cookies: HTTP State Management Mechanism](draft-ietf-httpbis-rfc6265bis-cookies-http-state-management-mechanism.md) - IETF * [draft-meunier-web-bot-auth-architecture](draft-meunier-web-bot-auth-architecture.md) - IETF * [draft-meunier-web-bot-auth-http-signature](draft-meunier-web-bot-auth-http-signature.md) - IETF * [draft-mozleywilliams-dnsop-dnsaid — DNS for AI Discovery](draft-mozleywilliams-dnsop-dnsaid-dns-for-ai-discovery.md) - IETF * [EDPB — 101 complaints concerning EU-U.S. data transfers (Google Analytics)](edpb-101-complaints-concerning-eu-u-s-data-transfers-google-analytics.md) - EDPB * [EDPB Guidelines 03/2022 on deceptive design patterns in social media](edpb-guidelines-03-2022-on-deceptive-design-patterns-in-social-media.md) - EDPB * [EDPB Guidelines 2/2023 on Technical Scope of Art. 5(3) ePrivacy Directive](edpb-guidelines-2-2023-on-technical-scope-of-art-5-3-eprivacy-directive.md) - EDPB * [EDPB Guidelines 4/2019 on Article 25 Data Protection by Design and by Default](edpb-guidelines-4-2019-on-article-25-data-protection-by-design-and-by-default.md) - EDPB * [EDPB Guidelines on Transparency under Regulation 2016/679](edpb-guidelines-on-transparency-under-regulation-2016-679.md) - EDPB * [ePrivacy Directive 2002/58/EC, Article 5(3)](eprivacy-directive-2002-58-ec-article-5-3.md) - EUR-Lex * [Equalize Digital — Accessibility Checker documentation](equalize-digital-accessibility-checker-documentation.md) - Equalize Digital * [EU Web Accessibility Directive](eu-web-accessibility-directive.md) - European Commission * [FAQPage (FAQ) structured data](faqpage-faq-structured-data.md) - Google Search Central * [Fetch Standard — Cross-Origin-Resource-Policy header](fetch-standard-cross-origin-resource-policy-header.md) - WHATWG * [Fetch Standard — MIME type checks](fetch-standard-mime-type-checks.md) - WHATWG * [GDPR Article 5 — Principles relating to processing of personal data](gdpr-article-5-principles-relating-to-processing-of-personal-data.md) - EU GDPR * [GDPR Articles 13 and 14 — Information to be provided](gdpr-articles-13-and-14-information-to-be-provided.md) - EU GDPR * [Global Privacy Control specification](global-privacy-control-specification.md) - W3C Community Group * [Google — Consolidate duplicate URLs with canonicals](google-consolidate-duplicate-urls-with-canonicals.md) - Google Search Central * [Google — Create good meta descriptions](google-create-good-meta-descriptions.md) - Google Search Central * [Google — Google-Extended](google-google-extended.md) - Google Search Central * [Google — Influencing your title links in search results](google-influencing-your-title-links-in-search-results.md) - Google Search Central * [Google — Links and link building](google-links-and-link-building.md) - Google Search Central * [Google Search Central — Google Discover and your website](google-search-central-google-discover-and-your-website.md) - Google * [Google Search Central — How to deal with planned site downtime](google-search-central-how-to-deal-with-planned-site-downtime.md) - Google Search Central * [Google Search Central — Localized versions of your pages](google-search-central-localized-versions-of-your-pages.md) - Google Search Central * [Google Search Central — Managing multi-regional and multilingual sites](google-search-central-managing-multi-regional-and-multilingual-sites.md) - Google Search Central * [Google Search Central — Robots meta tag, data-nosnippet, and X-Robots-Tag](google-search-central-robots-meta-tag-data-nosnippet-and-x-robots-tag.md) - Google Search Central * [Google Search Central — Soft 404 errors](google-search-central-soft-404-errors.md) - Google Search Central * [Google SRE Book — Monitoring Distributed Systems](google-sre-book-monitoring-distributed-systems.md) - Google SRE * [Google SRE Workbook — SLO engineering case studies](google-sre-workbook-slo-engineering-case-studies.md) - Google SRE * [Google — Strict CSP](google-strict-csp.md) - web.dev * [How Google interprets the robots.txt specification](how-google-interprets-the-robots-txt-specification.md) - Google Search Central * [HSTS Preload List Submission](hsts-preload-list-submission.md) - Google Chrome * [HTML Living Standard — Constraint validation](html-living-standard-constraint-validation.md) - WHATWG * [HTML Living Standard — Headings and sections](html-living-standard-headings-and-sections.md) - WHATWG * [HTML Living Standard — Link type: icon](html-living-standard-link-type-icon.md) - WHATWG * [HTML Living Standard — Link types: alternate](html-living-standard-link-types-alternate.md) - WHATWG * [HTML Living Standard — Link types: canonical](html-living-standard-link-types-canonical.md) - WHATWG * [HTML Living Standard — Other metadata names: theme-color](html-living-standard-other-metadata-names-theme-color.md) - WHATWG * [HTML Living Standard — Specifying the document's character encoding](html-living-standard-specifying-the-document-s-character-encoding.md) - WHATWG * [HTML Living Standard — Standard metadata names](html-living-standard-standard-metadata-names.md) - WHATWG * [HTML Living Standard — Standard metadata names: color-scheme](html-living-standard-standard-metadata-names-color-scheme.md) - WHATWG * [HTML Living Standard — Standard metadata names: robots](html-living-standard-standard-metadata-names-robots.md) - WHATWG * [HTML Living Standard — Tabular data](html-living-standard-tabular-data.md) - WHATWG * [HTML Living Standard — The DOCTYPE](html-living-standard-the-doctype.md) - WHATWG * [HTML Living Standard — The enterkeyhint attribute](html-living-standard-the-enterkeyhint-attribute.md) - WHATWG * [HTML Living Standard — The inputmode attribute](html-living-standard-the-inputmode-attribute.md) - WHATWG * [HTML Living Standard — The lang and xml:lang attributes](html-living-standard-the-lang-and-xml-lang-attributes.md) - WHATWG * [HTML Living Standard — The script element](html-living-standard-the-script-element.md) - WHATWG * [HTML Living Standard — The title element](html-living-standard-the-title-element.md) - WHATWG * [HTML Living Standard — The video element](html-living-standard-the-video-element.md) - WHATWG * [HTML Standard — Cross-Origin-Opener-Policy](html-standard-cross-origin-opener-policy.md) - WHATWG * [HTML Standard — Popover](html-standard-popover.md) - WHATWG * [HTML Standard — The hidden attribute](html-standard-the-hidden-attribute.md) - WHATWG * [HTML Standard — The translate attribute](html-standard-the-translate-attribute.md) - WHATWG * [HTTP Archive — Web Almanac: Media](http-archive-web-almanac-media.md) - HTTP Archive * [Human Interface Guidelines — Layout](human-interface-guidelines-layout.md) - Apple * [IAB Tech Lab — Content Signals](iab-tech-lab-content-signals.md) - IAB Tech Lab * [IANA — Link Relations Registry](iana-link-relations-registry.md) - IANA * [IANA — Well-Known URIs Registry](iana-well-known-uris-registry.md) - IANA * [ICANN — DNSSEC](icann-dnssec.md) - ICANN * [ICO — Data minimisation](ico-data-minimisation.md) - ICO * [ICO — Guidance on the use of cookies and similar technologies](ico-guidance-on-the-use-of-cookies-and-similar-technologies.md) - ICO * [ICO — Right to be informed](ico-right-to-be-informed.md) - ICO * [IETF AI Preferences WG (aipref) — drafts](ietf-ai-preferences-wg-aipref-drafts.md) - IETF * [Image sitemaps](image-sitemaps.md) - Google Search Central * [IndexNow protocol](indexnow-protocol.md) - IndexNow * [Internet Society — Deploying DNSSEC](internet-society-deploying-dnssec.md) - Internet Society * [Intersection Observer](intersection-observer.md) - W3C * [Introducing the Popover API](introducing-the-popover-api.md) - web.dev * [Introduction to robots.txt](introduction-to-robots-txt.md) - Google Search Central * [Introduction to structured data markup in Google Search](introduction-to-structured-data-markup-in-google-search.md) - Google Search Central * [Is It Agent Ready?](is-it-agent-ready.md) - Is It Agent Ready? * [JSON Feed 1.1](json-feed-1-1.md) - JSON Feed * [JSON-LD 1.1 Specification](json-ld-1-1-specification.md) - W3C * [Let's Encrypt — CAA](let-s-encrypt-caa.md) - Let's Encrypt * [Manage sitemaps for large sites](manage-sitemaps-for-large-sites.md) - Google Search Central * [Material Design — Accessibility: Layout and typography](material-design-accessibility-layout-and-typography.md) - Google * [MCP server tools: annotations & structured content](mcp-server-tools-annotations-structured-content.md) - MCP project * [MCP specification](mcp-specification.md) - MCP project * [MDN — 304 Not Modified](mdn-304-not-modified.md) - MDN * [MDN — Accept-Encoding](mdn-accept-encoding.md) - MDN * [MDN — Accept-Language header](mdn-accept-language-header.md) - MDN * [MDN — Alt-Svc](mdn-alt-svc.md) - MDN * [MDN — animation-timeline](mdn-animation-timeline.md) - MDN * [MDN — ARIA](mdn-aria.md) - MDN * [MDN — aria-current](mdn-aria-current.md) - MDN * [MDN — ARIA live regions](mdn-aria-live-regions.md) - MDN * [MDN — bfcache](mdn-bfcache.md) - MDN * [MDN — Cache-Control](mdn-cache-control.md) - MDN * [MDN — Compression Dictionary Transport](mdn-compression-dictionary-transport.md) - MDN * [MDN — contain](mdn-contain.md) - MDN * [MDN — Content-Encoding](mdn-content-encoding.md) - MDN * [MDN — Content-Location](mdn-content-location.md) - MDN * [MDN — Content-Security-Policy](mdn-content-security-policy.md) - MDN * [MDN — Content Security Policy (CSP)](mdn-content-security-policy-csp.md) - MDN * [MDN — content-visibility](mdn-content-visibility.md) - MDN * [MDN — Creating hyperlinks](mdn-creating-hyperlinks.md) - MDN * [MDN — Cross-Origin-Opener-Policy](mdn-cross-origin-opener-policy.md) - MDN * [MDN — Cross-Origin-Resource-Policy](mdn-cross-origin-resource-policy.md) - MDN * [MDN — CSP: frame-ancestors](mdn-csp-frame-ancestors.md) - MDN * [MDN — CSP: upgrade-insecure-requests](mdn-csp-upgrade-insecure-requests.md) - MDN * [MDN — CSS logical properties and values](mdn-css-logical-properties-and-values.md) - MDN * [MDN — CSS scroll-driven animations](mdn-css-scroll-driven-animations.md) - MDN * [MDN — decoding attribute](mdn-decoding-attribute.md) - MDN * [MDN — ](mdn-dialog.md) - MDN * [MDN — DNS — CAA records](mdn-dns-caa-records.md) - MDN * [MDN — Doctype](mdn-doctype.md) - MDN * [MDN — env() and the safe-area-inset-* variables](mdn-env-and-the-safe-area-inset-variables.md) - MDN * [MDN — Evolution of HTTP](mdn-evolution-of-http.md) - MDN * [MDN — :focus-visible](mdn-focus-visible.md) - MDN * [MDN — font-display](mdn-font-display.md) - MDN * [MDN — @font-face](mdn-font-face.md) - MDN * [MDN — Graceful degradation](mdn-graceful-degradation.md) - MDN * [MDN — `:has()`](mdn-has.md) - MDN * [MDN — Heading elements](mdn-heading-elements.md) - MDN * [MDN — hidden global attribute](mdn-hidden-global-attribute.md) - MDN * [MDN — HTML autocomplete attribute](mdn-html-autocomplete-attribute.md) - MDN * [MDN — HTML elements reference](mdn-html-elements-reference.md) - MDN * [MDN — HTTP caching](mdn-http-caching.md) - MDN * [MDN — HTTP conditional requests](mdn-http-conditional-requests.md) - MDN * [MDN — HTTP response status codes](mdn-http-response-status-codes.md) - MDN * [MDN —