> ## Documentation Index
> Fetch the complete documentation index at: https://docs.cow.bleu.builders/llms.txt
> Use this file to discover all available pages before exploring further.

# Orders

> Understanding CoW Protocol's intent-based order system, structure, lifecycle, and signing mechanisms

# Orders

CoW Protocol uses an intent-based order system where users express trading preferences off-chain, and solvers compete to find the best execution.

## Order Structure

Orders contain 12 parameters defining trading intent:

| Parameter           | Type      | Description                               |
| ------------------- | --------- | ----------------------------------------- |
| `sellToken`         | `address` | Token to sell (ERC20)                     |
| `buyToken`          | `address` | Token to buy (ERC20)                      |
| `sellAmount`        | `uint256` | Amount of sell token                      |
| `buyAmount`         | `uint256` | Minimum/maximum amount of buy token       |
| `validTo`           | `uint32`  | Order expiration timestamp                |
| `appData`           | `bytes32` | Application-specific metadata             |
| `feeAmount`         | `uint256` | Fee amount in sell token                  |
| `kind`              | `bytes32` | Order kind (sell or buy)                  |
| `partiallyFillable` | `bool`    | Whether the order can be partially filled |
| `sellTokenBalance`  | `bytes32` | Source of sell tokens                     |
| `buyTokenBalance`   | `bytes32` | Destination of buy tokens                 |
| `receiver`          | `address` | Recipient of bought tokens                |

## Order Types

### Sell Orders

Specify an exact amount to sell with a minimum buy amount guaranteed:

* `sellAmount` is the exact amount of sell tokens to exchange
* `buyAmount` is the minimum acceptable amount of buy tokens

### Buy Orders

Specify an exact amount to buy with a maximum sell amount capped:

* `buyAmount` is the exact amount of buy tokens to receive
* `sellAmount` is the maximum amount of sell tokens to spend

## Order UID

Each order receives a unique 56-byte UID combining:

* **Order digest** (32 bytes) - EIP-712 hash of the order
* **Owner address** (20 bytes) - The order creator
* **Validity timestamp** (4 bytes) - Expiration time

## EIP-712 Signing

Orders use typed EIP-712 signatures enabling hardware wallet support. The protocol hashes order data with a domain separator to create an order digest.

```solidity theme={null}
bytes32 orderDigest = keccak256(
    abi.encodePacked(
        "\x19\x01",
        domainSeparator,
        orderStructHash
    )
);
```

## Signature Schemes

CoW Protocol supports four signing methods:

| Scheme        | Use Case                                             |
| ------------- | ---------------------------------------------------- |
| **EIP-712**   | Standard typed data signing (recommended)            |
| **eth\_sign** | Legacy signing for compatibility                     |
| **EIP-1271**  | Smart contract wallet validation (e.g., Gnosis Safe) |
| **PreSign**   | On-chain pre-authorization                           |

## Balance Sources

Users can source tokens from three different balance types:

* **ERC20** - Standard ERC20 token balances
* **External** - Balancer Vault external balances
* **Internal** - Balancer Vault internal balances

## Order Validation

During settlement, five checks occur:

1. **Signature validity** - Verifies the order was signed by the owner
2. **Expiration status** - Ensures `validTo` has not passed
3. **Limit price compliance** - Checks that clearing prices respect order limits
4. **Fill amount verification** - Prevents overfilling
5. **Sufficient balance** - Confirms the user has enough tokens

## Order Lifecycle

```mermaid theme={null}
stateDiagram-v2
    [*] --> Created
    Created --> Submitted
    Submitted --> Filled
    Submitted --> PartiallyFilled
    Submitted --> Expired
    Submitted --> Cancelled
    PartiallyFilled --> Filled
    PartiallyFilled --> Expired
    PartiallyFilled --> Cancelled
```

* **Created** - Order signed off-chain
* **Submitted** - Order sent to the order pool
* **Filled** - Order completely executed
* **PartiallyFilled** - Order partially executed (if `partiallyFillable` is true)
* **Expired** - Order `validTo` timestamp has passed
* **Cancelled** - Order invalidated by the owner