# AIPREF Content-Usage Attachment AIPREF

[3 · Permit](/category/permit/)

| AIPREF Content-Usage Attachment |
| --- |
| Category | [Permit](/category/permit/) |
| Governed by | IETF AI Preferences Working Group (ai-control@ietf.org mailing list) |
| Status | Internet-Draft, work in progress; "About This Document" note says it is to be removed before publishing as an RFC |
| Phase | working group |
| Implementation | unknown |
| Adoption | unmeasured |
| Version | draft-ietf-aipref-attach-05 (2026-08-19) |
| Specification | [https://www.ietf.org/archive/id/draft-ietf-aipref-attach-05.html](https://www.ietf.org/archive/id/draft-ietf-aipref-attach-05.html) |
| Found at | /robots.txt |
| Last checked | 2026-09-06 |

[Permit](/category/permit/) The AIPREF Content-Usage Attachment draft is an IETF AI Preferences Working Group Internet-Draft that defines how a publisher attaches machine-readable AI-use preferences to HTTP-served content [[1]](#ref-1). It solves the 'where do the preference values live' half of the AIPREF pair: it specifies two attachment mechanisms, a Robots Exclusion Protocol extension (a new directive inside robots.txt) and an HTTP response header field named Content-Usage, and states explicitly that it updates RFC 9309 (the Robots Exclusion Protocol RFC) so the two documents are read together [[1]](#ref-1).

## Overview
It does not itself define the vocabulary of preference values — which use categories exist (e.g. AI training, search, input to generative answers) and how they are expressed — that is the companion AIPREF Vocabulary draft (draft-ietf-aipref-vocab), which this document's tokens reference. It also does not define enforcement: like robots.txt, compliance depends entirely on the crawler choosing to read and honour the signal.

As of this verification (2026-09-06) the current version is draft-ietf-aipref-attach-05, dated 2026-08-19, confirming the prior finding that -05 was current as of August 2026 [[1]](#ref-1). The document is still explicitly marked as a work in progress with boilerplate noting the 'About This Document' section is to be stripped before RFC publication, and it carries no RFC number yet. Development happens in the open on GitHub under ietf-wg-aipref/drafts with a public issue tracker and mailing list (ai-control@ietf.org) [[1]](#ref-1).

Implementers are not named in the draft itself; this record does not find independent evidence of shipping crawlers or CMS/CDN products emitting the Content-Usage header or the new robots.txt directive as of this verification — adoption is unmeasured rather than zero, since a systematic scan was not run for this record. What is unresolved: how this attachment mechanism will interact with the pre-existing, unrelated Cloudflare Content Signals Policy convention, which also extends robots.txt with different signal names (search/ai-input/ai-train) and predates this draft; and whether major crawler operators (Google, OpenAI, Anthropic, Perplexity) will adopt the IETF vocabulary once it reaches RFC status rather than continuing with their own per-vendor robots.txt tokens, which are already in wide use (see ai-crawler-tokens-robots).

## Discovery and probe

robots.txt directive and/or Content-Usage HTTP response header, both updating RFC 9309 · /robots.txt

```
GET {origin}/robots.txt
parse:     Presence of a 'Content-Usage' line in a robots.txt group, or a Content-Usage HTTP response header on the fetched resource itself
on absent: Publisher has not attached machine-readable AI-use preferences via either attachment method; no inference can be drawn about actual policy
```

Live check run by [the MCP probe](/mcp/server-card): GET /robots.txt. A Content-Usage line in robots.txt attaches AIPREF preferences to the site.

```
{
 "path": "/robots.txt",
 "expect": {
  "text_match": "(?im)^content-usage:"
 },
 "note": "A Content-Usage line in robots.txt attaches AIPREF preferences to the site."
}
```

## History
- 2026-09-05 — seeded from Exa Agent research run
- 2026-09-06 — verified against ietf.org/archive/id/draft-ietf-aipref-attach-05.html

## Instances

No instances recorded yet.

## See also

- [AIPREF Vocabulary](/protocols/aipref-vocabulary/)

## References

- draft-ietf-aipref-attach-05, dated 2026-08-19, defines attachment via the Robots Exclusion Protocol and an HTTP header field, and states it updates RFC 9309. — [https://www.ietf.org/archive/id/draft-ietf-aipref-attach-05.html](https://www.ietf.org/archive/id/draft-ietf-aipref-attach-05.html) (2026-08-19) VERIFIED
- The working document is developed on GitHub by the ietf-wg-aipref organization with an issue tracker and a rendered latest draft. — [https://datatracker.ietf.org/doc/html/draft-ietf-aipref-vocab-07](https://datatracker.ietf.org/doc/html/draft-ietf-aipref-vocab-07) (2026-08-19) REPORTED

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