---
title: "LRFS — Glossary | LLMind"
description: "The LLM-Ready File Specification — LLMind's open spec for in-file semantic metadata and signing."
url: https://llmind.org/glossary/lrfs/
source_format: html
---
[← Glossary](https://llmind.org/glossary/)

# LRFS

**The LLM-Ready File Specification — LLMind's open spec for in-file semantic metadata and signing.**

LRFS (LLM-Ready File Specification) is LLMind's published open specification for embedding semantic metadata inside files and cryptographically signing it. It defines exactly how metadata is structured in RDF/XML, stored in XMP packets, canonicalized, and signed so that any compliant reader — whether built by LLMind or a third party — can verify and extract the metadata. LRFS is language-agnostic and format-agnostic: it works with JPEG, PNG, PDF, TIFF, audio, video, and any format that supports XMP.

## What LRFS defines

The spec covers the XMP packet structure, the custom namespace (`https://llmind.org/ns/1.0/`), the RDF schema for each semantic layer (description, entities, structure, transcription, lineage), and the signing scheme. For signing, LRFS defaults to HMAC-SHA256 for private verification and supports ed25519 for public-key scenarios. The spec also defines canonicalization rules so that identical metadata produces identical signatures across tools and languages, and it specifies conformance levels so partial implementations can still interoperate.

## Versioning and adoption

LRFS v1.x is the current major version. Breaking changes require a v2.0 release with a new namespace URI, preserving backward compatibility for legacy files. By publishing an open spec and maintaining backward compatibility, LLMind enables third parties to build conformant readers and writers — turning LRFS from a single tool into a category. Organizations can enrich their own files without vendor lock-in.

## Related terms

-   [LLM-ready file](https://llmind.org/glossary/llm-ready-file/)
-   [XMP namespace](https://llmind.org/glossary/xmp-namespace/)
-   [Signed semantic metadata](https://llmind.org/glossary/signed-semantic-metadata/)

## See also

-   [LRFS spec](https://llmind.org/spec/)
-   [Payload format](https://llmind.org/spec/payload-format/)
-   [Conformance](https://llmind.org/spec/conformance/)
-   [Learn](https://llmind.org/learn/)