# #id?

## `#id?`

Optional privately stored unique [identification](https://error.angular-package.dev/draft-5/getting-started/basic-concepts#identification) of the described [problem](https://error.angular-package.dev/draft-5/getting-started/basic-concepts#problem) of generic type variable [`Id`](https://error.angular-package.dev/draft-5/generic-type-variables#commonerror-less-than-id-greater-than).

{% code title="common-error.class.ts" %}

```typescript
#id?: Id;
```

{% endcode %}

### Type

#### [<mark style="color:green;">`Id`</mark>](https://error.angular-package.dev/draft-5/generic-type-variables#wrap-opening)