> ## Documentation Index > Fetch the complete documentation index at: https://docs.metalntwx.com/llms.txt > Use this file to discover all available pages before exploring further. # Transactions > Supported Ethereum envelopes, Metal's 0x7f transaction type, and transaction admission rules. Metal accepts replay-protected legacy (`0x00`), EIP-2930 (`0x01`), EIP-1559 (`0x02`), EIP-4844 blob (`0x03`), and MIP20 (`0x7f`) transaction envelopes. ## Envelope matrix | Type | Envelope | Gas token | Authorization list | Status | | - | - | - | - | - | | `0x00` | Replay-protected legacy | Chain default | No | Accepted | | `0x01` | EIP-2930 | Chain default | No | Accepted | | `0x02` | EIP-1559 | Chain default | No | Accepted | | `0x03` | EIP-4844 blob | Chain default | No | Accepted with an EIP-7594 sidecar | | `0x04` | EIP-7702 SetCode | Native Ethereum semantics | Yes | Rejected | | `0x7e` | Scheduled system transaction | Scheduler escrow | No | Produced by block execution; rejected at admission | | `0x7f` | MIP20 | Signer-selected MIP20 | Optional | Accepted | Standard Ethereum envelopes pay gas in the chain's default MIP20 token. Use them with existing Ethereum tooling when the default token is suitable. Use the `0x7f` envelope when the signer must choose another allowlisted MIP20 gas token or include an EIP-7702 authorization. A `0x7e` transaction is one due entry of the `Scheduler` predeploy at `0x00000000000000000000000000000000000000fe`, run by block execution at the head of the block; RPC renders it as an EIP-1559-shaped transaction from that address with a zero signature, to the entry's call target, or to the `Scheduler` itself with the ABI-encoded calls when the entry makes several. See [Scheduled Transactions](https://docs.metalntwx.com/build/contracts/schedule-a-contract-call.md). Standard blob transactions require an EIP-7594 network sidecar and submission through a validator RPC endpoint. They pay execution gas and a separate blob fee in the default MIP20 token. See [Blob Transactions and Sidecars](https://docs.metalntwx.com/reference/network-fundamentals/blobs.md) for the network form and retention rules. > [!NOTE] > > Metal does not accept Ethereum's native `0x04` SetCode transaction envelope. > It supports an EIP-7702 authorization only when that authorization is carried > inside a signed Metal `0x7f` envelope. ## Asset standards inside a transaction The envelope defines the signer, gas payment, authorization list, and outer EVM call. The called contract defines the asset state transition and policy checks. | Standard | Role during execution | How an application submits it | | - | - | - | | [MIP20](https://docs.metalntwx.com/learn/mip20/token-and-account-model.md) | Moves transparent balances and supplies Metal gas tokens | Call the asset from any accepted envelope. Use `0x7f` when the signer selects a gas token or includes an EIP-7702 authorization | | [MIP410](https://docs.metalntwx.com/learn/mip410/shielded-payments.md) | Shields MIP20 value, verifies shielded payments, and unshields value | Submit the contract call and proof data in any accepted envelope | MIP410 operations use the accepted outer envelopes. The signer pays gas with the default MIP20 token or the token selected by a `0x7f` envelope. ## Admission rules Before a transaction enters the pool, Metal checks: * the signature and recovered sender; * an EIP-155 chain ID that matches the network; * a supported envelope type; * `tx.value == 0`; * an allowlisted MIP20 gas token; * the fee floor and maximum fee bound; * a gas limit no greater than `100,000,000`; * sufficient balance for maximum gas cost and recognized same-token debits; and * transaction-pool nonce and replacement rules. Blob admission also verifies the EIP-7594 sidecar, its KZG commitments and cell proofs, and a positive blob-fee bid within the fee cap. Affordability includes `blobGasUsed × maxFeePerBlobGas` in addition to maximum execution gas cost. An admitted transaction can still revert during EVM execution. Admission proves that the envelope and current affordability are valid, not that the contract call will succeed. ## MIP20 envelope fields Fields appear below in their RLP encoding order. | Field | Type | Description | | - | - | - | | `chain_id` | `uint64` | Chain identifier. Testnet: `63825` | | `nonce` | `uint64` | Sender's transaction count (include pending) | | `max_priority_fee_per_gas` | `uint128` | Priority fee per gas unit, in MIP20 token base units | | `max_fee_per_gas` | `uint128` | Maximum fee per gas unit. On the testnet, set equal to the priority fee (`block.basefee == 0`) | | `gas_limit` | `uint64` | Maximum gas to consume | | `to` | `address` or empty | Target contract or recipient. An empty destination encodes contract creation | | `value` | `uint256` | Must be `0`. Non-zero value is rejected at admission | | `input` | `bytes` | ABI-encoded calldata | | `access_list` | `[]` | Standard EIP-2930 access list. Usually empty | | `authorization_list` | `[]` | Optional EIP-7702 smart-account authorizations | | `gas_token` | `address` | MIP20 token address used to pay gas | > [!WARNING] > > `value` must be `0`. Metal has no native gas asset. Any transaction with > `tx.value != 0` is rejected at the mempool admission gate. ## How gas payment works Admission requires the signer to cover `max_fee_per_gas × gas_limit` from the identity-keyed MIP20 balance. Before executing the transaction body, the Metal EVM debits `min(max_fee_per_gas, max_priority_fee_per_gas) × gas_limit`. A `0x7f` transaction names that token in `gas_token`; a standard Ethereum transaction uses the chain's default gas token. After execution, Metal refunds the unused portion and leaves `block.coinbase` with the fee for gas consumed. The execution layer updates MIP20 storage directly without an `approve` or `transferFrom` call. Contract reverts roll back application state while the signer still pays for consumed gas. A blob transaction also pays its full blob fee, which is not refunded. > [!WARNING] > > The signer must hold enough `gas_token` for the maximum gas cost plus any > recognized same-token debit. Both amounts use `_balances[signer]`. `max_fee_per_gas` must be at most `1_000_000_000_000` base units. Because `block.basefee == 0`, the effective gas price is `min(max_fee_per_gas, max_priority_fee_per_gas)` and must be at least `1`. ## Optional authorization list An ordinary EOA does not need an `authorization_list` to send MIP20 tokens. Include one only when the account is opting into or changing a smart-account implementation. The MIP20 EIP-712 signature binds the authorization-list hash. Each authorization's `chainId` must equal Metal's chain ID; chain-agnostic (`chainId = 0`) authorizations are rejected. The authorization and the selected MIP20 gas token therefore share one signed Metal transaction. Clients should not translate the request into a standalone `0x04` envelope, because native `0x04` admission is rejected. ## EIP-712 signing The `0x7f` envelope is signed as EIP-712 typed data, not a raw RLP transaction. The typed data domain uses the `MIP20Factory` address as the verifying contract: * **Domain name:** `"Metal"` * **Domain version:** `"1"` * **Verifying contract:** `0x0000000000000000000000000000000000000f4C` (MIP20Factory) * **Chain ID:** matches `chain_id` field Use the SDKs rather than building this by hand: ```typescript TypeScript theme={null} import { sendMip20Call } from "@metalntwx/metal-ts"; const txHash = await sendMip20Call({ walletClient, // viem WalletClient with a connected account publicClient, // viem PublicClient connected to Metal RPC to: contractAddress, data: "0x...", // ABI-encoded calldata gasToken: usdTokenAddress, gasFallback: 200_000n, // gas limit if estimation fails }); ``` ## Testnet defaults | Setting | Value | | - | - | | Chain ID | `63825` | | RPC URL | `https://rpc-testnet.metalntwx.com/v1/` | | Default gas token | `*USDZ` (`0x000000000000000000000000000000000000B5D5`) | | `max_priority_fee_per_gas` | `1` | | `max_fee_per_gas` | `1` | Get your endpoint ID from the [Metal console](https://console-testnet.metalntwx.com). See [RPC endpoint setup](https://docs.metalntwx.com/start/connect-to-testnet.md#2-create-an-rpc-endpoint) for the setup steps. > [card] [Fees](https://docs.metalntwx.com/build/prepare/estimate-and-record-fees.md) > > Follow the MIP20 debit, refund, and validator reward. > [card] [TypeScript SDK](https://docs.metalntwx.com/reference/typescript-sdk.md) > > Build and submit `0x7f` transactions with the Metal SDK. This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.