{
  "meta": {
    "title": "ai.txt Specification",
    "description": "The canonical specification for ai.txt files - AI usage permissions and intent signals.",
    "version": "1.7.0",
    "versionDate": "2026-05-11",
    "canonicalUrl": "https://www.ai-visibility.org.uk/specifications/ai-txt/",
    "publisher": {
      "name": "365i",
      "url": "https://www.365i.co.uk/"
    },
    "license": {
      "name": "Creative Commons Attribution 4.0 International",
      "identifier": "CC-BY-4.0",
      "url": "https://creativecommons.org/licenses/by/4.0/"
    },
    "datePublished": "2026-01-12T00:00:00Z",
    "dateModified": "2026-05-11T00:00:00Z",
    "language": "en-GB"
  },
  "specification": {
    "filename": "ai.txt",
    "location": "Website root directory",
    "urlPattern": "https://example.com/ai.txt",
    "mimeType": "text/plain",
    "encoding": "UTF-8",
    "purpose": "Declare how AI systems should interact with and represent the organisation. Defines what AI may and must not do when processing, citing, or generating content about the entity.",
    "format": {
      "type": "Structured text",
      "description": "Section-based plain text with bracketed section headers",
      "syntax": {
        "sections": "[section-name]",
        "comments": "# Comment text",
        "keyValue": "key: value",
        "lists": "- list item"
      }
    },
    "sections": {
      "required": [
        {
          "name": "[identity]",
          "description": "Business identifier linking this file to the organisation",
          "fields": [
            {
              "field": "name",
              "description": "Official organisation name",
              "required": true
            },
            {
              "field": "url",
              "description": "Canonical website URL",
              "required": true
            }
          ]
        },
        {
          "name": "[permissions]",
          "description": "What AI systems are permitted to do",
          "format": "List of permitted actions"
        },
        {
          "name": "[restrictions]",
          "description": "What AI systems must not do",
          "format": "List of prohibited actions"
        }
      ],
      "recommended": [
        {
          "name": "[attribution]",
          "description": "How AI systems should attribute information from this source",
          "fields": [
            {
              "field": "required",
              "description": "Whether attribution is required (yes/no)",
              "example": "yes"
            },
            {
              "field": "format",
              "description": "Preferred citation format",
              "example": "According to [Organisation Name]..."
            }
          ]
        },
        {
          "name": "[contact]",
          "description": "Contact information for AI-related queries",
          "fields": [
            {
              "field": "ai-queries",
              "description": "Email for AI-related questions"
            }
          ]
        },
        {
          "name": "[scope]",
          "description": "Define the scope of these permissions",
          "fields": [
            {
              "field": "applies-to",
              "description": "What content these rules apply to"
            }
          ]
        }
      ],
      "optional": [
        {
          "name": "[licensing]",
          "description": "Content licensing information",
          "fields": [
            {
              "field": "content-license",
              "description": "License for website content"
            },
            {
              "field": "ai-training",
              "description": "Whether content may be used for AI training"
            }
          ]
        },
        {
          "name": "[metadata]",
          "description": "File metadata",
          "fields": [
            {
              "field": "version",
              "description": "Version of this ai.txt file"
            },
            {
              "field": "last-updated",
              "description": "Date of last update"
            }
          ]
        }
      ]
    },
    "permissionTypes": {
      "common": [
        "cite-with-attribution",
        "summarise-content",
        "answer-questions",
        "describe-services",
        "provide-contact-information"
      ],
      "conditional": [
        "quote-with-source",
        "recommend-conditionally"
      ]
    },
    "restrictionTypes": {
      "common": [
        "imply-endorsement",
        "generate-fake-quotes",
        "provide-specific-advice",
        "guarantee-outcomes",
        "make-claims-beyond-scope"
      ]
    },
    "validation": {
      "rules": [
        "MUST include [identity] section with name and url",
        "MUST include [permissions] section",
        "MUST include [restrictions] section",
        "MUST be valid UTF-8 encoded plain text",
        "Section headers MUST use square brackets",
        "Key-value pairs MUST use colon separator"
      ],
      "commonErrors": [
        "Missing required sections",
        "Inconsistent section header format",
        "Contradictory permissions and restrictions",
        "Missing identity linkage",
        "Overly vague permission language"
      ]
    },
    "relationships": {
      "ai.json": "Machine-parseable equivalent - should contain consistent information",
      "llms.txt": "Identity information must match",
      "identity.json": "Organisation details must be consistent",
      "robots.txt": "Complements crawler access rules with behavioural guidance"
    }
  },
  "example": {
    "url": "https://www.ai-visibility.org.uk/specifications/examples/ai.txt",
    "business": "Horizon Strategic Consulting"
  },
  "versionHistory": [
    {
      "version": "1.7.0",
      "date": "2026-05-11",
      "changes": "Phase 6 standardisation release. Added /specifications/roadmap/ (theme-pegged forward plan with Active/Next/Future/On hold status flags), /specifications/extensions/ (rules for experimental x- prefixed files and the promotion path), and /specifications/i18n-a11y/ (multi-language publication, locale-tagged identity fields, RTL handling, accessibility of llms.html). Added the Discovery: directive to the robots-ai.txt specification (publishers MAY advertise AI Discovery Files on the same host). Added a formal media-type stance to the HTTP behaviour page (existing IANA types, no bespoke registrations). Expanded the file integrity and signing section on the security and privacy page with four candidate mechanisms, cross-cutting concerns, and interim publisher / consumer guidance. The Discovery: directive is the only normative addition to publisher behaviour; all other additions are forward-looking documentation."
    },
    {
      "version": "1.6.0",
      "date": "2026-05-11",
      "changes": "Phase 5 standardisation release. Added /specifications/related-standards/ (positioning vs llmstxt.org, IETF AI Preferences, robots.txt, Schema.org, BCP 14, JSON Schema 2020-12, SemVer) and /specifications/implementations/ (public record of conformant implementations, IETF-style). Added an explicit llmstxt.org backward-compatibility statement to the llms.txt specification. Added a formal multi-domain and subdomain scoping rule to both the llms.txt and identity.json specifications (host-scoped files, cross-host identity asserted via sameAs). No normative requirements changed for existing publishers; the new scoping rules formalise behaviour the specification already implied."
    },
    {
      "version": "1.5.0",
      "date": "2026-05-11",
      "changes": "Phase 4 standardisation release. Added /specifications/processing-model/ (seven-stage algorithm for conformant consumers), /specifications/consumer-guidance/ (what AI systems should do with AI Discovery Files), /specifications/test-vectors/ (canonical test suite framing), and reference-implementation framing on the AI Visibility Checker. No normative requirements changed."
    },
    {
      "version": "1.4.0",
      "date": "2026-05-11",
      "changes": "Phase 3 standardisation release. Added /specifications/versioning/ (Semantic Versioning 2.0.0 commitments, deprecation timeline, lifecycle), /specifications/governance/ (proposal lifecycle, editorial process, working principles), /specifications/security-privacy/ (trust model, content-injection patterns, GDPR considerations, integrity primitives roadmap), and /specifications/http-behaviour/ (status codes, redirects, soft-404 detection, caching, rate limits). No normative requirements changed."
    },
    {
      "version": "1.3.0",
      "date": "2026-05-11",
      "changes": "Phase 2 standardisation release. Added formal conformance specification (Essential / Recommended / Complete classes). Published machine-readable registry at /specifications/registry.json, spec meta-schema, and validator-output schema. Introduced versioned JSON Schema URLs (/v1/) alongside unversioned 'latest' aliases. Added optional BCP 47 language declaration field across all applicable AI Discovery Files. No normative requirements changed."
    },
    {
      "version": "1.2.0",
      "date": "2026-05-10",
      "changes": "Phase 1 standardisation release. Added 'Status of This Document' block (Stable). Normalised normative requirement keywords to uppercase per RFC 2119 and RFC 8174. Added References section linking to /specifications/conventions/ and /licensing/. No normative requirements changed."
    },
    {
      "version": "1.1.1",
      "date": "2026-02-13",
      "changes": "Added AI Visibility Directory registration guidance. Minor documentation update."
    },
    {
      "version": "1.1.0",
      "date": "2026-01-14",
      "changes": "Added expanded optional sections (scope, training, data-retention, updates) and Content Not Permitted guidance. Clarifies what should not be included in ai.txt files."
    },
    {
      "version": "1.0.0",
      "date": "2026-01-12",
      "changes": "Initial specification release. Establishes canonical structure for ai.txt files with permissions, restrictions, and attribution sections."
    }
  ]
}