> For the complete documentation index, see [llms.txt](https://docs.ainetwork.ai/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.ainetwork.ai/ain-blockchain/ai-network-design/transactions/nonce.md).

# Nonce

AIN supports three transaction ordering modes. All modes still require a valid signature, the active chain ID, an allowed timestamp, sufficient resources, and permission under the state rules.

| Mode              | `nonce`      | Ordering                                                                           |
| ----------------- | ------------ | ---------------------------------------------------------------------------------- |
| Numbered          | Integer >= 0 | Must match the account's next nonce; a new account starts at 0.                    |
| Unordered         | -1           | No account nonce ordering; duplicate transactions are rejected.                    |
| Timestamp ordered | -2           | Timestamp must be strictly greater than the account's preceding ordered timestamp. |

Query the account's nonce through the SDK/API instead of calculating it from a count of historical transactions. Concurrent clients must coordinate numbered nonces. A stale numbered nonce is invalid; do not assume an arbitrary future nonce will remain queued until accepted.

Use a fresh millisecond timestamp for a new transaction. After an execution-chain-ID transition, a pre-transition timestamp or an obsolete chain-domain signature is rejected even with nonce -1. To retry an uncertain submission, query its transaction hash before creating another transaction.