# What is a canon document?

A canon document is the version a team has agreed is true: when documents disagree, it decides and the others defer to it.

Updated on 22 October 2026.

## How it works

The word comes from fiction, where canon is the material a franchise treats as having really happened. Teams borrow it for the same reason: among drafts, explorations and old versions, one document holds the decision.

Canon is a status, not a location. A document becomes canon when someone with the authority says so, and stops being canon when it is marked obsolete or superseded by another document.

## An example

A game’s lore has three drafts of a city’s history. The writers mark the third as canon and the other two as exploration, so a quest designer, and the AI assistant drafting dialogue, both read the third.

## Common mistakes

- Leaving several documents that each look final.
- Deleting old versions instead of marking them superseded, which loses why things changed.
- Telling people what is canon but not the AI tools that read the same documents.

## In Nodary

A Nodary document can be marked canon, exploration, obsolete, or superseded by another document. Agents are told a document’s status before they read it, a document can be checked against the project’s canon, and when two documents disagree Nodary shows both passages side by side.

**What Nodary does not do:** it does not decide what is canon: a person sets the status, and a contradiction is only resolved when someone chooses to.

- [Single source of truth, a guide](https://nodary.ai/guides/single-source-of-truth)

Try it on your own documents. The Free plan needs no card. [Create a free workspace](https://nodary.ai/sign-up)

## Sources

- [Canon (fiction), Wikipedia](https://en.wikipedia.org/wiki/Canon_(fiction))
- [Single source of truth, Wikipedia](https://en.wikipedia.org/wiki/Single_source_of_truth)

## Related terms

- [Single source of truth: keep one version of every decision](https://nodary.ai/guides/single-source-of-truth): Why documents drift, and seven practices that keep one current version for people and AI agents.
- [Decision log](https://nodary.ai/glossary/decision-log): A decision log is a running record of a team’s decisions, each with its date, who decided, why, and the options set aside.
- [Context window](https://nodary.ai/glossary/context-window): A context window is how much text, counted in tokens, a language model takes into account at once, instructions and documents included.

https://nodary.ai/glossary/canon-document