# Systems

URL: /code/file-conventions/systems · Id: `page:code/file-conventions/systems`

> A file in systems/ overrides one inherited System, its Settings, extra Nouns or Integrations, and an untouched System has no file.

A file in `systems/` overrides one inherited [System](/business/nouns/system): its [Settings](/business/nouns/setting), extra [Nouns](/business/nouns/noun), or the [Integrations](/business/nouns/integration) bound to it. An untouched System has no file; the business view is [Systems](/systems).

```text
systems/
├── billing.mdx       dunning and invoice Settings
└── scheduling.mdx    a calendar Integration
```

## Reference
The file name is the System id. Frontmatter only. The group, such as finance, is a field of the System and never a folder, so regrouping moves no file.

| Key | Type | Holds |
| --- | --- | --- |
| `settings` | map | The System's Settings this [Startup](/business/nouns/startup) changes |
| `nouns` | Noun names | Nouns the System adds for this Startup |
| `integrations` | map | Outside accounts bound to the System, with scope |

## Examples
### Minimal
```mdx title="systems/billing.mdx"
---
settings: { retryDays: [3, 5, 7] }
---
```

### Leaseline
`systems/billing.mdx`:

```mdx title="systems/billing.mdx"
---
settings:
  retryDays: [3, 5, 7]
  invoiceMemo: Thank you for using Leaseline.
  currency: USD
---
```

## What it builds
The [StartupBuilder](/code/builders/startup) compiles the file into the System's instance for this Startup.

- the System's Settings, overriding the [Startup Template](/business/nouns/startup-template)'s
- an `Integration` per entry, connected with `Integration.connect` and reported by `Integration.connected`
- in the finance group, Stripe objects under the Startup's own connected account

## Good to know
- Each System's page lists its Settings, Nouns and [Verbs](/business/nouns/verb); payments start at the [finance group](/systems/finance).