Fuel Specs

Icon LinkTransaction

enum TransactionType : uint8 {
    Script = 0,
    Create = 1,
    Mint = 2,
}

name	type	description
`type`	TransactionType	Transaction type.
`data`	One of TransactionScript, TransactionCreate, or TransactionMint	Transaction data.

Transaction is invalid if:

type > TransactionType.Create
gasLimit > MAX_GAS_PER_TX
blockheight() < maturity
inputsCount > MAX_INPUTS
outputsCount > MAX_OUTPUTS
witnessesCount > MAX_WITNESSES
No inputs are of type InputType.Coin or InputType.Message with input.dataLength == 0
More than one output is of type OutputType.Change for any asset ID in the input set
Any output is of type OutputType.Change for any asset ID not in the input set
More than one input of type InputType.Coin for any Coin ID in the input set
More than one input of type InputType.Contract for any Contract ID in the input set
More than one input of type InputType.Message for any Message ID in the input set

When serializing a transaction, fields are serialized as follows (with inner structs serialized recursively):

uint8, uint16, uint32, uint64: big-endian right-aligned to 8 bytes.
byte[32]: as-is.
byte[]: as-is, with padding zeroes aligned to 8 bytes.

When deserializing a transaction, the reverse is done. If there are insufficient bytes or too many bytes, the transaction is invalid.

Icon LinkTransactionScript

enum ReceiptType : uint8 {
    Call = 0,
    Return = 1,
    ReturnData = 2,
    Panic = 3,
    Revert = 4,
    Log = 5,
    LogData = 6,
    Transfer = 7,
    TransferOut = 8,
    ScriptResult = 9,
    MessageOut = 10,
    Mint = 11
    Burn = 12
}

name	type	description
`gasPrice`	`uint64`	Gas price for transaction.
`gasLimit`	`uint64`	Gas limit for transaction (including predicate gas).
`maturity`	`uint32`	Block until which tx cannot be included.
`scriptLength`	`uint16`	Script length, in instructions.
`scriptDataLength`	`uint16`	Length of script input data, in bytes.
`inputsCount`	`uint8`	Number of inputs.
`outputsCount`	`uint8`	Number of outputs.
`witnessesCount`	`uint8`	Number of witnesses.
`receiptsRoot`	`byte[32]`	Merkle root of receipts.
`script`	`byte[]`	Script to execute.
`scriptData`	`byte[]`	Script input data (parameters).
`inputs`	Input`[]`	List of inputs.
`outputs`	Output`[]`	List of outputs.
`witnesses`	Witness`[]`	List of witnesses.

Given helper len() that returns the number of bytes of a field.

Transaction is invalid if:

Any output is of type OutputType.ContractCreated
scriptLength > MAX_SCRIPT_LENGTH
scriptDataLength > MAX_SCRIPT_DATA_LENGTH
scriptLength * 4 != len(script)
scriptDataLength != len(scriptData)
gasLimit is less than the sum of all predicateGasUsed for InputType.Coin or InputType.Message where predicate length is greater than zero.

Note: when signing a transaction, receiptsRoot is set to zero.

Note: when verifying a predicate, receiptsRoot is initialized to zero.

Note: when executing a script, receiptsRoot is initialized to zero.

The receipts root receiptsRoot is the root of the binary Merkle tree of receipts. If there are no receipts, its value is set to the root of the empty tree, i.e. 0xe3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855.

Icon LinkTransactionCreate

name	type	description
`gasPrice`	`uint64`	Gas price for transaction.
`gasLimit`	`uint64`	Gas limit for transaction (including predicate gas).
`maturity`	`uint32`	Block until which tx cannot be included.
`bytecodeLength`	`uint16`	Contract bytecode length, in instructions.
`bytecodeWitnessIndex`	`uint8`	Witness index of contract bytecode to create.
`storageSlotsCount`	`uint16`	Number of storage slots to initialize.
`inputsCount`	`uint8`	Number of inputs.
`outputsCount`	`uint8`	Number of outputs.
`witnessesCount`	`uint8`	Number of witnesses.
`salt`	`byte[32]`	Salt.
`storageSlots`	`(byte[32], byte[32]])[]`	List of storage slots to initialize (key, value).
`inputs`	Input`[]`	List of inputs.
`outputs`	Output`[]`	List of outputs.
`witnesses`	Witness`[]`	List of witnesses.

Transaction is invalid if:

Any input is of type InputType.Contract or InputType.Message where input.dataLength > 0
Any output is of type OutputType.Contract or OutputType.Variable or OutputType.Message
More than one output is of type OutputType.Change with asset_id of zero
Any output is of type OutputType.Change with non-zero asset_id
It does not have exactly one output of type OutputType.ContractCreated
bytecodeLength * 4 > CONTRACT_MAX_SIZE
tx.data.witnesses[bytecodeWitnessIndex].dataLength != bytecodeLength * 4
bytecodeWitnessIndex >= tx.witnessesCount
The keys of storageSlots are not in ascending lexicographic order
The computed contract ID (see below) is not equal to the contractID of the one OutputType.ContractCreated output
storageSlotsCount > MAX_STORAGE_SLOTS
The Sparse Merkle tree root of storageSlots is not equal to the stateRoot of the one OutputType.ContractCreated output

Creates a contract with contract ID as computed here.

Icon LinkTransactionMint

The transaction is created by the block producer and is not signed. Since it is not usable outside of block creation or execution, all fields must be fully set upon creation without any zeroing.

name	type	description
`txPointer`	TXPointer	The location of the `Mint` transaction in the block.
`outputsCount`	`uint8`	Number of outputs.
`outputs`	Output`[]`	List of outputs.

Transaction is invalid if:

Any output is not of type OutputType.Coin
Any two outputs have the same asset_id
txPointer is zero or doesn't match the block.

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