# `Mpan`

A UK electricity supply's 13-digit number.

Use it to switch or identify an electricity supply. For gas, use [`Mprn`](/docs/types/type-mprn.md).

## Shape

One value, held as text in one set form, with no parts: `2300004567890`.

## Example

```jadpo
Mpan("1200012345679")
```

`Mpan(raw)` checks the text, and text that isn't one breaks the `format` rule.

`text.parse(raw, as: Mpan)` reads one from text that comes from outside. Text that isn't one at all fails `malformed`, such as `1200012345678`, `120001234567` or `S 1200012345679`.

## Good to know

- It checks its own last digit, so a mistyped number is usually refused.
- `==` tells you whether two are the same. `<` and `list.sort_by` don't take it.
- A field that holds one counts as personal data (`contact`), so you don't mark it yourself.

## In JSON

A string, in a request, a response or `json.write`:

```json
"1200012345679"
"2300004567890"
```

## Details

<details>
<summary>Text form, storage, how it is shown, and operations</summary>

`Mpan` is in the group Other with a published standard, and has been in Jadpo since 0.1.0.

### Text form

`text.from` writes one standard text form, the same form `text.parse` reads back: `1200012345679` and `2300004567890`.

### How it is stored

It is stored in one column named for the field, of type `text`. `2300004567890` is stored as `'2300004567890'`.

### How it is shown to people

`text.format(value, locale:)` shows it to people in their locale.

With `locale: Locale.en_gb`:

| Value | Shown |
|---|---|
| `1200012345679` | `1200012345679` |
| `2300004567890` | `2300004567890` |

### Operations

It also takes `text.parse`, `text.from`, `text.format`, `json.read`, `json.write` and `==`. [How every standard type behaves](/docs/every-standard-type-meets-one-contract.md) says how they work.

</details>