> For the complete documentation index, see [llms.txt](https://docs.tumbler.app/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.tumbler.app/glossary.md).

# Glossary

## Who this is for

Provider technical teams who want to use the same language as us and verify public contract terms.

## What you can do

* Quickly find key term definitions.
* Check field and header names.
* Align on wording before changing your endpoints.

## Examples

* "subscription URL" - address where the fetcher gets configuration.
* "add link" - `tumbler://add?link=...`, which opens import in the app.
* "crypt3" - encrypted source link that hides the real subscription URL.
* "version\_id" - monotonic snapshot version identifier.
* "node" - one connectable VPN server.

## See also

* [subscription/metadata.md](/subscription-contract/metadata.md)
* [features/overview.md](/features/overview.md)
* [security/url-protection-and-crypt3.md](/getting-started/url-protection-and-crypt3.md)

## Terms

* **subscription URL** - HTTP/HTTPS address from which the backend fetcher retrieves the provider subscription.
* **source link** - value passed to `tumbler://add?link=...`: raw subscription URL or `schema://crypt3/<token>`.
* **add link** - public user link/QR: `tumbler://add?link=<url-encoded source>`.
* **crypt3** - mechanism that encrypts the subscription URL into a source link like `schema://crypt3/<token>`, so the client does not see the original address.
* **snapshot** - current representation of all available nodes, metadata, and limits.
* **version\_id** - value used to detect snapshot updates; must change on every meaningful change.
* **checksum** - string for fast response integrity checks (sha256/hex or etag).
* **node** - separate server or endpoint that can accept connections.
* **capability** - feature availability marker, for example balancing or **\[PAID]** session management.
* **fetcher** - our service that periodically polls the subscription URL.


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:

```
GET https://docs.tumbler.app/glossary.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.