# Reference

Look up exact values for endpoints, formats, rules, roles and error responses. For the ideas behind them, see the [concepts](https://docs.atlas.ilionx.dev/concepts.md). For step-by-step tasks, see the [guides](https://docs.atlas.ilionx.dev/guides.md). For definitions of terms, see the [glossary](https://docs.atlas.ilionx.dev/reference/glossary.md).

Replace `https://<atlas-host>` in examples with your ATLAS address.

| Page                                              | Contents                                                                                                  |
| ------------------------------------------------- | --------------------------------------------------------------------------------------------------------- |
| [Gateway](https://docs.atlas.ilionx.dev/reference/gateway.md)                             | Endpoints, authentication, headers, request and response behaviour, parameter handling and limits         |
| [API keys](https://docs.atlas.ilionx.dev/reference/api-keys.md)                           | Key format, acting context, expiry rules, who can create and revoke keys, and how keys are refused        |
| [Roles and permissions](https://docs.atlas.ilionx.dev/reference/roles-and-permissions.md) | What each role can do, how roles come from your identity provider, and why a member can be suspended      |
| [Budgets](https://docs.atlas.ilionx.dev/reference/budgets.md)                             | Budget rules, limits and enforcement, pricing and currency, the business time zone and billing statements |
| [Errors](https://docs.atlas.ilionx.dev/reference/errors.md)                               | The error formats that the web app and the gateway return, and what the common errors mean                |
| [Glossary](https://docs.atlas.ilionx.dev/reference/glossary.md)                           | Definitions of the terms used across the documentation                                                    |