# AIPREF Content-Usage Attachment vs AIPREF Vocabulary

Both belong to the AIPREF group on this map. The map lists them as complementary: sites and agents commonly implement both. AIPREF Vocabulary is a prerequisite of AIPREF Content-Usage Attachment. They share the acronym AIPREF but are unrelated protocols.

[3 Permit](/category/permit/) [AIPREF Content-Usage Attachment](/protocols/aipref-content-usage-attachment/) · [3 Permit](/category/permit/) [AIPREF Vocabulary](/protocols/aipref-vocabulary/)

|  | [AIPREF Content-Usage Attachment](/protocols/aipref-content-usage-attachment/) AIPREF | [AIPREF Vocabulary](/protocols/aipref-vocabulary/) AIPREF |
| --- | --- | --- |
| Lifecycle step | 3 Permit: What may the agent do here? | 3 Permit: What may the agent do here? |
| Answers | How does a publisher attach its AI-use preferences to content served over HTTP, so an automated system can find them? | What controlled set of values expresses a publisher's AI-use preferences, independent of how they are attached to content? |
| Governed by | IETF AI Preferences Working Group (ai-control@ietf.org mailing list) | IETF AI Preferences Working Group (ai-control@ietf.org mailing list) |
| Status (issuer's words) | Internet-Draft, work in progress; "About This Document" note says it is to be removed before publishing as an RFC | Internet-Draft, work in progress; explicitly states its contents 'DO NOT REFLECT CONSENSUS of the Working Group' |
| Phase | working group | working group |
| Version | draft-ietf-aipref-attach-05 (2026-08-19) | draft-ietf-aipref-vocab-08 (2026-09-14) |
| Form / transport | well-known file | document format |
| Found at | /robots.txt | Not independently discoverable; values are carried by the Content-Usage attachment mechanism (robots.txt directive or HTTP header) |
| Adoption | unmeasured | unmeasured |
| Evidence | 1 verified, 1 reported | 2 verified, 1 reported |
| Primary use case | Control AI crawling and training use | Control AI crawling and training use |
| Last verified | 2026-10-18 (current) | 2026-10-18 (current) |
| 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) | [https://datatracker.ietf.org/doc/html/draft-ietf-aipref-vocab-08](https://datatracker.ietf.org/doc/html/draft-ietf-aipref-vocab-08) |

## When to use which

- Choose AIPREF Content-Usage Attachment when your question is “How does a publisher attach its AI-use preferences to content served over HTTP, so an automated system can find them?” and you accept its maturity: phase working group, adoption unmeasured.
- Choose AIPREF Vocabulary when your question is “What controlled set of values expresses a publisher's AI-use preferences, independent of how they are attached to content?” and you accept its maturity: phase working group, adoption unmeasured.

Guidance is derived from the two records (question, phase, adoption, prerequisites, pairings), not from opinion. Each record's page carries its numbered references.

## Read the full articles

- [AIPREF Content-Usage Attachment](/protocols/aipref-content-usage-attachment/): How does a publisher attach its AI-use preferences to content served over HTTP, so an automated system can find them?
- [AIPREF Vocabulary](/protocols/aipref-vocabulary/): What controlled set of values expresses a publisher's AI-use preferences, independent of how they are attached to content?

Ask the MCP server to compare any two: the compare-protocols prompt, or get on both ids. [Connect](/connect/).

[aipref-content-usage-attachment.json](/data/protocols/aipref-content-usage-attachment.json) · [aipref-vocabulary.json](/data/protocols/aipref-vocabulary.json) · [Markdown](/compare/aipref-content-usage-attachment-vs-aipref-vocabulary/index.md)