EIP-2718 — Typed Transaction Envelope

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EIP-2718: Typed Transaction Envelope

Originally, Ethereum had one transaction format. EIP-2930 (access lists) and EIP-1559 (base fee) needed new fields, but breaking the existing format would have required a hard fork. EIP-2718 introduces a type byte as the first byte of serialised transactions:

Type	Defined by
0xc0-0xfe	Legacy (RLP-encoded transaction directly)
0x00	Reserved
0x01	EIP-2930 (access list)
0x02	EIP-1559 (fee market)
0x03	EIP-4844 (blob)
0x04	EIP-7702 (set-code)

Neo Equivalent

Neo has a single transaction type by design. Adding new capabilities (access lists via witness scopes, fee handling, etc.) is done by extending the existing transaction structure. Backward compatibility is handled at the network protocol level rather than by introducing parallel formats. The serialisation is binary, versioned by the network message version.

Live on Neo TestNet

Both implementations are deployed on Neo N3 TestNet (network magic 894710606).

Implementation	Contract Hash	Deploy Tx
Solidity (neo-solc)	0x4e2300b8426b26eb8bbf57398a53ad810e313bf6	0x3f88a613…63d867
Neo C# (nccs)	0xb600afb3c034ff11a3e25a26fa03b58e263d9cb8	0x989908a1…c2ed1f

Checked-in snapshot matches on the EVM reference type constants; the manifest now also asserts Neo's neoTxVersion on both implementations. Source pairs under docs/standards-mirror/deployments/eip-2718/.

// EIP-2718 type-prefixed serialisation example:
//
//   serialized_tx = type_byte || rlp([type-specific fields])
//
// Wallets must know how to construct each type. EIP-1559 (type 0x02):
//
//   0x02 || rlp([
//     chainId, nonce, maxPriorityFeePerGas, maxFeePerGas,
//     gasLimit, to, value, data, accessList, v, r, s
//   ])
//
// Type 0x03 (blob, EIP-4844):
//
//   0x03 || rlp([
//     chainId, nonce, maxPriorityFeePerGas, maxFeePerGas,
//     gasLimit, to, value, data, accessList,
//     maxFeePerBlobGas, blobVersionedHashes,
//     v, r, s
//   ])
//
// Each new EIP adds another type. Wallets, indexers, RPC clients all need to
// support every type they want to handle.

// Neo's transaction shape (one type):
//
//   class Transaction {
//     byte Version;           // network version
//     uint Nonce;
//     long SystemFee;
//     long NetworkFee;
//     uint ValidUntilBlock;
//     Signer[] Signers;       // up to 16 signers, each with scopes
//     TransactionAttribute[] Attributes;  // OracleResponse, HighPriority, etc.
//     byte[] Script;          // VM bytecode to execute
//     Witness[] Witnesses;    // one per Signer, in same order
//   }
//
// New capabilities are added via:
//   - Bumping Version
//   - Adding new TransactionAttribute kinds
//   - Adding new Signer scope flags
//
// All fields are present in every transaction. There's no parallel format —
// older nodes simply reject transactions whose Version they don't support.

using Neo;
using Neo.SmartContract.Framework;
using Neo.SmartContract.Framework.Attributes;
using Neo.SmartContract.Framework.Native;

namespace R3E.Examples;

[DisplayName("TxIntrospection")]
public class TxIntrospection : SmartContract
{
    /// <summary>Read transaction-level fields available to any contract during execution.</summary>
    public static (uint, ulong, ulong, byte) CurrentTx()
    {
        var tx = (Transaction)Runtime.ScriptContainer;
        return (tx.ValidUntilBlock, (ulong)tx.SystemFee, (ulong)tx.NetworkFee, tx.Version);
    }
}