# Untitled undefined type in ArgumentsDeclaration Schema

```txt
https://amazonalexa.com/ask/2020/12/ArgumentsDeclaration#/items/properties/defaultExpression
```

Indicates whether the argument is required. If the argument is not provided in an 'Call' expression, this expression will be used instead.

| Abstract            | Extensible | Status         | Identifiable            | Custom Properties | Additional Properties | Access Restrictions | Defined In                                                                                    |
| :------------------ | :--------- | :------------- | :---------------------- | :---------------- | :-------------------- | :------------------ | :-------------------------------------------------------------------------------------------- |
| Can be instantiated | No         | Unknown status | Unknown identifiability | Forbidden         | Allowed               | none                | [ArgumentsDeclaration.json\*](../../schemas/ArgumentsDeclaration.json "open original schema") |

## defaultExpression Type

merged type ([Details](argumentsdeclaration-argument-declaration-properties-defaultexpression.md))

one (and only one) of

*   [Call](actiondeclaration-properties-annotations-call.md "check type definition")

*   [property reference](arguments-definitions-arg-expression-oneof-property-reference.md "check type definition")

*   [name](arguments-definitions-arg-expression-oneof-name.md "check type definition")