> ## Documentation Index
> Fetch the complete documentation index at: https://docs.debridge.com/llms.txt
> Use this file to discover all available pages before exploring further.
# introduction
> Method Parameters, AutoParams Structure, and Flags.
# Interaction with deBridge Infrastructure
Interaction with the deBridge infrastructure is as simple as calling the `send` method of the `debridgeGate` smart contract deployed on all supported
blockchains. The method can be called by any arbitrary address — either EOA or smart contracts.
```solidity theme={null}
function send(
address _tokenAddress,
uint256 _amount,
uint256 _chainIdTo,
bytes memory _receiver,
bytes memory _permit,
bool _useAssetFee,
uint32 _referralCode,
bytes calldata _autoParams
) external payable;
```
## Method Parameters
| Parameter Name | Type | Description |
| --------------- | ------- | ------------------------------------------------------------------------------------------- |
| `_tokenAddress` | address | Address of the token being sent (`address(0)` for chain base assets like ETH) |
| `_amount` | uint256 | Token amount to be transferred |
| `_chainIdTo` | uint256 | Id of the receiving chain |
| `_receiver` | bytes | Address of the receiver |
| `_permit` | bytes | [EIP-2612](https://eips.ethereum.org/EIPS/eip-2612) permit signature (if token supports it) |
| `_useAssetFee` | bool | Should be set to `false`. Reserved for future governance usage |
| `_referralCode` | uint32 | Your generated referral code |
| `_autoParams` | bytes | Structure that enables passing arbitrary messages and call data |
If you integrate with or build applications on top of the deBridge infrastructure, make sure you specify your referral code that can be generated by
pressing the INVITE FRIENDS button at [https://app.debridge.com/](https://app.debridge.com/). Governance may thank you later for being an early builder.
***
## AutoParams Structure
`_autoParams` allows passing arbitrary messages and call data to be executed as an external call to the receiver address on the destination chain. It
also enables setting an `executionFee`, which rewards the wallet/keeper that completes the transaction. It enables a crypto-economic design where gas
fees are paid from the blockchain where the transaction is initiated. The `_autoParams` field has the following structure:
```solidity theme={null}
struct SubmissionAutoParamsTo {
uint256 executionFee;
uint256 flags;
bytes fallbackAddress;
bytes data;
}
```
| Parameter Name | Type | Description |
| ----------------- | ------- | ------------------------------------------------------------------------------------------------------ |
| `executionFee` | uint256 | Suggested reward (in tokens) paid to executor on the destination chain |
| `flags` | uint256 | Bitmask flags that define execution logic |
| `fallbackAddress` | bytes | Address to receive tokens if external call fails |
| `data` | bytes | Message/call data to be passed to the receiver on destination chain during the external call execution |
***
## Flags
Flags are a bitmask that customize transaction execution flow on the destination chain. You can combine multiple flags by setting respective bits to
`1` simultaneously.
```solidity theme={null}
library Flags {
uint256 public constant UNWRAP_ETH = 0;
uint256 public constant REVERT_IF_EXTERNAL_FAIL = 1;
uint256 public constant PROXY_WITH_SENDER = 2;
uint256 public constant SEND_HASHED_DATA = 3;
uint256 public constant SEND_EXTERNAL_CALL_GAS_LIMIT = 4;
uint256 public constant MULTI_SEND = 5;
}
```
| Flag Name | Value | Description |
| ------------------------------ | ----- | --------------------------------------------------------------------------------------- |
| `UNWRAP_ETH` | 0 | Automatically unwrap base asset (e.g., convert WETH to ETH) |
| `REVERT_IF_EXTERNAL_FAIL` | 1 | Revert entire tx if external call fails |
| `PROXY_WITH_SENDER` | 2 | Enforces sender validation via `submissionNativeSender` and `submissionChainIdFrom` |
| `SEND_HASHED_DATA` | 3 | Only hashed data is passed; used to prevent unauthorized claims |
| `SEND_EXTERNAL_CALL_GAS_LIMIT` | 4 | Specifies minimal gas limit for the external call (included in first 4 bytes of `data`) |
| `MULTI_SEND` | 5 | Executes data via Gnosis Multisend implementation inside deBridge `callProxy` |
***
`PROXY_WITH_SENDER` flag should be used if the receiving smart contract must validate that the message sender is trusted. When set, the deBridge
protocol stores `submissionNativeSender` and `submissionChainIdFrom`, allowing the recipient contract to verify the sender.
The receiving smart contract can retrieve the `callProxy` address from the `debridgeGate` smart contract. Use
[`onlyControllingAddress`](https://github.com/debridge-finance/debridge-twap-oracle/blob/f981f700d07108fce5509fabd2fd0f10157ae6d6/contracts/debridge-twap-oracle/BridgeAppBase.sol#L62)
modifier or inherit from
[`BridgeAppBase.sol`](https://github.com/debridge-finance/debridge-twap-oracle/blob/f981f700d07108fce5509fabd2fd0f10157ae6d6/contracts/debridge-twap-oracle/BridgeAppBase.sol)
to implement this validation logic properly.