# `Icd10Code`

A diagnosis's ICD-10 code, with its dot: `I21.9`.

Use it to record a diagnosis in a form health systems share. For clinical concepts beyond diagnoses, use [`SnomedConcept`](/docs/types/type-snomed-concept.md).

## Shape

One value, held as text in one set form, with no parts: `S52.521A`.

## Example

```jadpo
Icd10Code("I21.9")
```

`Icd10Code(raw)` checks the text, and text that isn't one breaks the `format` rule.

`text.parse(raw, as: Icd10Code)` reads one from text that comes from outside. Text that isn't one at all fails `malformed`, such as `I219`, `i21.9` or `121.9`.

## Good to know

- Write it in capitals with its dot. `I219` is 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 (`health`), so you don't mark it yourself.

## In JSON

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

```json
"I21.9"
"J45"
"S52.521A"
```

## Details

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

`Icd10Code` is in the group Health, 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: `I21.9`, `J45` and `S52.521A`.

### How it is stored

It is stored in one column named for the field, of type `text`. `J45` is stored as `'J45'`.

### How it is shown to people

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

With `locale: Locale.en_gb`:

| Value | Shown |
|---|---|
| `I21.9` | `I21.9` |
| `J45` | `J45` |
| `S52.521A` | `S52.521A` |

### 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>