# 2020-12

The [2020-12 metaschema patch](../schema/2020-12/patch/metaschema-patch.json) sets [`additionalProperties`](https://json-schema.org/understanding-json-schema/reference/object#additionalproperties) to `false` and adds the following properties to [JSON Schema 2020-12](https://json-schema.org/draft/2020-12).

```{tip}
To reference the extended metaschema, use its canonical URI:

[`http://json-schema-extension.readthedocs.io/1__0__0/2020-12/metaschema.json`](http://json-schema-extension.readthedocs.io/1__0__0/2020-12/metaschema.json)
```

```{jsonschema} ../schema/2020-12/patch/metaschema-patch.json
:pointer:
```