# RefSubject.Identifier

Describes the identifier type.

## Signatures

```ts
export type Identifier<T> = T extends RefSubject.Service<infer R, infer _Id, infer _A, infer _E> ? R : never;
```

## Why

Extracts the Context service identifier type represented by a RefSubject service facade.

## Ownership and lifetime

Identifier is a contract and performs no acquisition. Implementations retain the errors,
services, interruption, and Scope requirements expressed by its members.