> ## Documentation Index
> Fetch the complete documentation index at: https://base-a060aa97-docs-add-b20-spec.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# IB20Asset.extraMetadata

> Generated B20 reference for extraMetadata(string).

[Related concept](/base-chain/specs/upgrades/beryl/b20/specification/concepts/variants-asset-vs-stablecoin)

## Signature

```solidity theme={null}
function extraMetadata(string calldata key) external view returns (string memory);
```

| Field               | Value                   |
| ------------------- | ----------------------- |
| Selector            | `0x4ddf9da0`            |
| Canonical signature | `extraMetadata(string)` |

## Description

The value of the named metadata entry, or the empty string if not set. A
variant-agnostic key/value store; the issuer chooses the key namespace
(e.g. `"category"`, `"region"`, `"reference"`).
Param: key Metadata entry key.
Return: Current value, or the empty string.

## Access control

Read-only or ERC-20-standard access rules unless the NatSpec states otherwise.

## Policy interaction

No direct policy interaction.

## Example

```solidity theme={null}
IB20Asset(target).extraMetadata(arg0);
```

## Related

* [IB20Asset reference](/base-chain/specs/upgrades/beryl/b20/specification/reference/interfaces/IB20Asset)
* [Constants & addresses](/base-chain/specs/upgrades/beryl/b20/specification/reference/constants-and-addresses)