# llms.txt v2: what changed in the second edition
> How v2 of the llms.txt proposal differs from v1: discovery through rel=alternate and rel=describedby, files in subpaths, two Markdown URL forms, the new role of Optional
Page: https://llms-full-txt.ru/en/specification/changes/
Site index: https://llms-full-txt.ru/en/llms.txt
## In short
v2 of the `llms.txt` proposal was published on August 10, 2026. The file format itself barely changed. What changed is everything around it: how an agent finds the file, what a file in a subpath means, and how the file is consumed.
v1 came out on September 3, 2024. Both were written by Jeremy Howard (Answer.AI). It remains a proposal by a single author, not an IETF or W3C standard.
A short account of the event: [The second edition of llms.txt is out](https://llms-full-txt.ru/en/blog/llms-txt-v2/).
## Differences at a glance
| Topic | v1 (2024) | v2 (2026) |
|---|---|---|
| Discovery | only the `/llms.txt` address convention | two link relations: `rel="alternate" type="text/markdown"` and `rel="describedby"`, in HTML or in a `Link` header |
| File in a subpath | permitted, meaning undefined | covers the URLs under its path; the most specific applicable file wins |
| Markdown version of a page | `page.html.md` only | two forms: `page.html.md` and `page.md` |
| `Optional` section | special mechanical meaning | a convention for secondary links |
| `llms_txt2ctx`, `llms-ctx.txt` | part of the proposal | removed |
| How the file is consumed | not described | an agent views or searches the file, then follows links |
| `/.well-known/` | not discussed | rejected, with an explanation |
| `llms-full.txt`, `llms-small.txt` | absent | absent |
## Discovery
The most common request from the community: given a page, how does an agent find its Markdown version, or the `llms.txt` that covers it, without guessing the URL.
v2 answers with standard link relations:
```html
```
The same can be sent as a response header. That form works for any resource, not only HTML, and can be configured on the server without touching pages:
```text
Link: ; rel="alternate"; type="text/markdown", ; rel="describedby"
```
More on the relations and headers: [Discovery of the file and Markdown versions](https://llms-full-txt.ru/en/specification/discovery/).
## Files in subpaths
v1 allowed `llms.txt` outside the root without saying what that meant. v2 defines it:
- a file covers the URLs under its path;
- where more than one file applies, the most specific one is used.
```text
/llms.txt -> the whole site
/docs/llms.txt -> everything in /docs/
```
This lets authors who control only part of a domain take part.
## Two Markdown URL forms
v1 specified a single form: `.md` appended to the full page URL. Some publishing tools replace the extension instead. v2 allows both:
```text
page.html -> page.html.md
page.html -> page.md
/docs/ -> /docs/index.html.md or /docs/index.md
```
## The consumption model
v1 described the `llms_txt2ctx` tool, which expanded a file into a ready context for a model. v2 states the expectation directly: an agent views or searches `llms.txt`, then follows the relevant links. The links should therefore point to LLM-friendly content.
Along with the tool, the proposal dropped:
- the `llms-ctx.txt` and `llms-ctx-full.txt` files;
- the special meaning of the `Optional` section, which told the tool what to omit.
`Optional` remains as a convention for secondary links.
## Why not /.well-known/
v2 explains why it does not use a `/.well-known/` address (RFC 8615). Such URIs exist only at the origin root. Many authors control only a path on a shared host and cannot add a file to the root. Like `index.html`, an `llms.txt` describes the path where it sits.
## What did not change
- Only the H1 is required.
- The order of parts: H1, blockquote, details without headings, H2 sections with link lists.
- The list item format: a link and optional notes after a colon.
- The file forbids nothing and does not control access.
## Absent from both revisions
- `llms-full.txt` and `llms-small.txt`. These files emerged as a practice of documentation platforms and are not in the proposal text.
- Requirements for `Content-Type`.
- A section on security and untrusted content.
- A rule for the language of the root file on a multilingual site.
The last three are open questions in the proposal repository.
## What a site owner should do
1. If the site already has an `llms.txt`, there is no need to redo it: the format is the same.
2. Check the links in the file: where possible they should point to Markdown versions of pages.
3. If Markdown versions exist, add `rel="alternate" type="text/markdown"` to the pages.
4. Add `rel="describedby"` pointing to the covering `llms.txt`.
5. Do not rely on any special handling of the `Optional` section.
:::note[What is known about adoption]
v2 is new. In a check of 46 sites on October 3, 2026, the `rel="describedby"` relation was found on one. Some documentation platforms send their own non-standard headers instead.
:::