# Attestation

## Attestation

This struct represents an on-chain attestation record. This record is not deleted after revocation.

`schemaId`: The `Schema` that this Attestation is based on. It must exist.

`linkedAttestationId`: Useful if the current Attestation references a previous Attestation. It can either be 0 or an existing attestation ID.

`attestTimestamp`: When the attestation was made. This is automatically populated by `_attest(...)`.

`revokeTimestamp`: When the attestation was revoked. This is automatically populated by `_revoke(...)`.

`attester`: The attester. At this time, the attester must be the caller of `attest()`.

`validUntil`: The expiration timestamp of the Attestation. Must respect `Schema.maxValidFor`. 0 indicates no expiration date.

`dataLocation`: Where `Attestation.data` is stored. See `DataLocation.DataLocation`.

`revoked`: If the Attestation has been revoked. It is possible to make a revoked Attestation.

`recipients`: The intended ABI-encoded recipients of this Attestation. This is of type `bytes` to support non-EVM repicients.

`data`: The raw data of the Attestation based on `Schema.schema`. There is no enforcement here, however. Recommended to use `abi.encode`.

```solidity
struct Attestation {
  uint64 schemaId;
  uint64 linkedAttestationId;
  uint64 attestTimestamp;
  uint64 revokeTimestamp;
  address attester;
  uint64 validUntil;
  DataLocation dataLocation;
  bool revoked;
  bytes[] recipients;
  bytes data;
}
```

## OffchainAttestation

This struct represents an off-chain attestation record. This record is not deleted after revocation.

`attester`: The attester. At this time, the attester must be the caller of `attestOffchain()`.

`timestamp`: The `block.timestamp` of the function call.

```solidity
struct OffchainAttestation {
  address attester;
  uint64 timestamp;
}
```