Protocol Constants and Limits

Use this page for values enforced by the Metal testnet, protocol contracts, or transaction admission.

Network

Constant	Value
Network name	Metal Testnet
Chain ID	`63825` (`0xf951`)
RPC URL	`https://rpc-testnet.metalntwx.com/v1/<endpoint-id>`
Wallet currency display	`USD Zero` (`USDZ`), 18 decimals
Explorer	`https://testnet.metalntwx.com`
Faucet	`https://faucet.metalntwx.com`
Consensus	Simplex
Native asset	None
Required transaction `value`	`0`
EVM revision	Osaka
Finality status method	`consensus_status`
Finality certificate method	`metal_getFinalityCertificate`
Future timestamp tolerance	`60,000` milliseconds, reducing to `2,000` milliseconds from the block where the scheduler activates
EVM `block.timestamp` precision	Seconds
Additive block timestamp field	`timestampMillisPart`, from `0` to `999`

Get your endpoint ID from the Metal console. See RPC endpoint setup for the setup steps.

Fixed system contracts

Contract addresses lists every fixed system contract and the ones Metal Testnet does not have yet. Application contracts use their deployment addresses.

Transaction and gas limits

Limit	Value	Enforcement
Accepted envelope types	`0x00`, `0x01`, `0x02`, `0x03`, `0x7f`	Transaction admission. `0x03` requires an EIP-7594 sidecar
Testnet block gas limit	`500,000,000`	Network genesis configuration
Per-transaction gas cap	`100,000,000`	Transaction admission and execution
Native transaction value	Exactly `0`	Transaction admission
Maximum `max_fee_per_gas`	`1_000_000_000_000` gas-token base units	Transaction admission
Minimum effective gas price	`1` gas-token base unit per gas	Transaction admission
Base fee	`0`	EVM block environment
Selectable gas token	Factory-allowlisted MIP20	`0x7f` admission
Standard-envelope gas token	Chain default MIP20	Transaction admission
EIP-7702 authorization transport	`authorization_list` inside `0x7f`	Transaction decoding

The effective gas price is min(max_fee_per_gas, max_priority_fee_per_gas).

Blobs and interoperability

Limit	Value	Scope
Blobs per block	`6`	Sum across all blob transactions in the block
Blob sidecar retention	At least `18` days	Verified sidecars persisted by validators, eligible for pruning afterwards
Blob fee	`blobGasUsed × maxFeePerBlobGas`	Charged in full in the default gas token, with no refund
Interop message tree depth	`32`	Metal outbox
Finality certificate retention	`100,000` certificates by default	Node-local retention, not a time-based availability guarantee

See Blobs and Finality Certificates for retrieval conditions.

MIP20

Limit or invariant	Value
Gas-accounting balance slot	Storage slot `0`
ERC-3009 EOA signature	`65`-byte ECDSA signature, or the split `v`, `r`, `s` form
ERC-3009 contract signature	`bytes` form checked through ERC-1271 when the signer has code and ECDSA does not authenticate it
EIP-712 version	`"1"`
Standard token deployment	`MIP20Factory.deployMIP20`
Receive-policy configuration	Each account configures its own rules through calls from its address
Default receive behavior	Accepts incoming credits, with `REVERT` refusal mode if rules are later enabled
Refusal modes	`REVERT = 0`, `QUARANTINE = 1`
Forced quarantine on refusal	Mints, MIP20 hold captures, and payouts from the token’s own balance
Recovery modes	`ORIGINATOR = 0`, `RECEIVER = 1`, `THIRD_PARTY = 2`
Quarantine receipt ID	`keccak256(abi.encode(receipt))`
Sender limit units	Token base units for amounts, arrivals for frequency, seconds for periods
Sender limit period	`0` for lifetime counting, otherwise fixed windows measured from the Unix epoch
Maximum amount and sender limits	A zero maximum disables the corresponding limit. Not on Metal Testnet yet

MIP20 screens incoming credits through ReceivePolicy, the receive policy contract at a fixed address. Ordinary transfers do not call sender or recipient code. The bytes form of ERC-3009 may make a read-only ERC-1271 signature check before changing state. Use a send policy contract to enforce outgoing controls, or a routing contract to forward funds. See Receive Policy for screening order, claim permissions, and the recipient fallback for contract originators.

MIP410

Limit or invariant	Value
Commitment tree depth	`32`
Maximum tree leaves	`4,294,967,296`
Commitment behavior	Append-only. Spending never removes a tree leaf
Known commitment tree roots	Every historical nonempty root, queried with `isKnownCommitmentRoot(root)`
VASP registry tree	Depth `10`, with `1,024` slots
Sanctions registry tree	Depth `20`, including the start-of-chain leaf
Accepted registry roots	Registration: current root and the previous root after an admission. Sanctions: current root only. Zero is never accepted
Note commitment	`Poseidon2(amount, asset_id, d, pk_x, pk_y, secret, P, bitmap_0, bitmap_1, depth, shieldTimestamp)`
Amount range	`0 < amount < 2^128`
MIP410 shielded pool	One protocol-deployed pool and one commitment tree across supported assets
Shielded payment and unshield inputs	Exactly two slots. The first slot is real, the second real or zero dummy
`Accept` resolution outputs	One recipient note commitment and one change note commitment. The change note commitment is canonically empty when no change remains
Active-hold input behavior	Input locks prevent another hold or spend
Accepted-hold input behavior	Input locks remain set permanently and nullifiers are recorded
Resolution entry points	`acceptPayment` and `rejectPayment`, each requiring a resolution proof and a policy-wrapper proof
Hold ID	The payment effect hash. A hold ID cannot be reused
Initiation deadline	`block.timestamp < deadline <= block.timestamp + maxHoldDuration()`
Shield timestamp	At most `3600` seconds before the block timestamp and never in the future
Expiry behavior	Makes an active hold reclaimable without releasing its inputs
Terminal hold states	`Accepted`, `Rejected`, or `Reclaimed`. Exactly one can succeed
Unshield destination	Authorized by the signature under the spending key, without a MIP410 destination-registration check
Payment transaction submission	Any account may submit prepared proofs or reclaim an expired hold. Administrative writes have separate authorization
Paused operations	Shield, initiate, accept, reject, unshield, bridge mint, and bridge withdraw. Reclaim and registry/admin writes remain available
Asset admission	Required for shielding. Revocation does not prevent unshielding
Transaction gas	Paid separately by the submitter account with MIP20

Contract addresses

Look up fixed system contract addresses.

Signing and typed data

Look up domains, primary types, and signed fields.

Transactions

Review envelope fields and admission order.

Block timestamps

Interpret seconds and millisecond header fields.

Network fundamentals

Assets and payments

Privacy

Compliance

Contracts and automation

Data and signatures

Interoperability

Network

Fixed system contracts

Transaction and gas limits

Blobs and interoperability

MIP20

MIP410

Contract addresses

Signing and typed data

Transactions

Block timestamps

​Network

​Fixed system contracts

​Transaction and gas limits

​Blobs and interoperability

​MIP20

​MIP410

Contract addresses

Signing and typed data

Transactions

Block timestamps

Network

Fixed system contracts

Transaction and gas limits

Blobs and interoperability

MIP20

MIP410