# Parser.Digit

The decimal digit character union.

## Signatures

```ts
type Digit = "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9";
```

## Why

Numeric characters participate in parameter names without becoming number values.

## Ownership and lifetime

`Digit` is a string-literal union used only during compiler evaluation and is erased from emitted JavaScript.