> ## 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.isAnnouncementIdUsed

> Generated B20 reference for isAnnouncementIdUsed(string).

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

## Signature

```solidity theme={null}
function isAnnouncementIdUsed(string calldata id) external view returns (bool);
```

| Field               | Value                          |
| ------------------- | ------------------------------ |
| Selector            | `0xc0da474e`                   |
| Canonical signature | `isAnnouncementIdUsed(string)` |

## Description

Whether `id` has previously been consumed by `announce`.
Param: id Announcement id to query.
Return: Whether `id` is used.

## 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).isAnnouncementIdUsed(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)