> For the complete documentation index, see [llms.txt](https://docs.internetobject.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.internetobject.org/schema-definition-language/data-types/binary.md).

# Binary

The binary type — byte data written as base64.

The **`binary`** type validates a sequence of bytes. In data, binary is written as a base64 literal with a `b` prefix: `b'SGVsbG8='`. (Base64 is the *encoding*; `binary` is the *type*.)

> For the literal value syntax, see [Binary values](/structure-and-syntax/values/binary.md).

## TypeDef

A `binary` MemberDef accepts the options below.

| Option     | Type            | Description                                                  |
| ---------- | --------------- | ------------------------------------------------------------ |
| `type`     | string          | The type name `binary`. First positional value.              |
| `default`  | binary          | Value used when the member is omitted.                       |
| `choices`  | array of binary | Restricts the value to a fixed set.                          |
| `len`      | int ≥ 0         | Exact length in bytes.                                       |
| `minLen`   | int ≥ 0         | Minimum length in bytes.                                     |
| `maxLen`   | int ≥ 0         | Maximum length in bytes.                                     |
| `optional` | bool            | If `true`, the member may be omitted. Shorthand: `?` suffix. |
| `null`     | bool            | If `true`, the member may be `null`. Shorthand: `*` suffix.  |

## Example

```ruby
avatar: { binary, maxLen: 65536 }
---
~ b'SGVsbG8='
```

## Implementation status (beta)

> **Binary is under development.** The `binary` schema type is being added to the reference implementation (it is not yet registered), and the `b'…'` value literal is not yet accepted by the parser. The design above is the agreed target; examples are not yet executable and are excluded from the example verifier.

## See Also

* [Binary values](/structure-and-syntax/values/binary.md)
* [TypeDef](/schema-definition-language/advanced-schema-concepts/typedef.md) · [MemberDef](/schema-definition-language/advanced-schema-concepts/memberdef.md)


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