# Reference

Everything `arc.yaml` can say, what OmniArc does with your compose file, and every error a check can report. The arc.yaml reference, the error pages and the CLI reference are generated from the code that reads your files, so they say what that code does.

- [arc.yaml reference](https://docs.omniarc.eu/reference/arc-yaml.md): every key, its type and default, an example, and the errors it can raise.
- [Compose support](https://docs.omniarc.eu/reference/compose-support.md): which compose features OmniArc refuses, and which run with a caveat.
- [Errors](https://docs.omniarc.eu/errors.md): every error `omniarc check` and `omniarc deploy` report for your files, with the file to fix.
- [JSON Schema for arc.yaml](https://docs.omniarc.eu/schema/arc.yaml.json), for completion and checking in your editor.
- [CLI reference](https://docs.omniarc.eu/cli.md): every command you can run.