# Form.MaskSlot

Named decoded segment in a bidirectional text mask.

## Signatures

```ts
export interface MaskSlot<Name extends string = string, Value = unknown> {
    readonly _tag: "MaskSlot";
    readonly name: Name;
    readonly codec: Schema.Codec<Value, string>;
    readonly length?: number;
    readonly charset?: RegExp | ((character: string) => boolean);
}
```

## Property: _tag

Discriminant used to distinguish slots from literal mask parts.

## Property: charset

Per-character acceptance test applied before Schema decoding.

## Property: codec

Bidirectional conversion between this slot's string segment and decoded value.

## Property: length

Exact encoded character count, when fixed-width.

## Property: name

Property name written into the decoded mask object.