# `Isin`

A securities identification number, naming a share or a bond: `US0378331005`.

Use it to name a tradable security. For a company, use [`Lei`](/docs/types/type-lei.md).

## Shape

One value, held as text in one set form, with no parts: `AU0000XVGZA3`.

## Example

```jadpo
Isin("US0378331005")
```

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

`text.parse(raw, as: Isin)` reads one from text that comes from outside. Text that isn't one at all fails `malformed`, such as `US0378331004`, `us0378331005` or `US037833100`.

## Good to know

- It is 12 characters in capitals, and it checks its own last digit.
- `==` tells you whether two are the same. `<` and `list.sort_by` don't take it.

## In JSON

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

```json
"US0378331005"
"GB0002634946"
"AU0000XVGZA3"
```

## Details

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

`Isin` is in the group Money and banking, 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: `US0378331005`, `GB0002634946` and `AU0000XVGZA3`.

### How it is stored

It is stored in one column named for the field, of type `text`. `GB0002634946` is stored as `'GB0002634946'`.

### How it is shown to people

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

With `locale: Locale.en_gb`:

| Value | Shown |
|---|---|
| `US0378331005` | `US0378331005` |
| `GB0002634946` | `GB0002634946` |
| `AU0000XVGZA3` | `AU0000XVGZA3` |

### 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>