> ## Documentation Index
> Fetch the complete documentation index at: https://docs.cowboy.lat/llms.txt
> Use this file to discover all available pages before exploring further.

# Transaction Fields

> Field descriptions of Cowboy transactions

## Introduction

This page lists the canonical fields of a user-submitted transaction and their semantics, aligning with the Cowboy whitepaper and CIPs.

<Tip>
  Cowboy implements dual metering (Cycles and Cells) with independent EIP‑1559‑style fee markets; users set per‑meter limits and max fee/tip parameters.
</Tip>

## Canonical Fields

* nonce (u64)
  * Monotonically increasing per-sender counter. Prevents replay and enforces ordering. The state transition function validates signature, nonce, and balance before execution (whitepaper).

* to (address, 20 bytes)
  * Target account. If the target is an EOA, the transaction performs a native transfer; if the target is an actor, the transaction invokes the actor’s handler.

* value (u128, CBY)
  * Amount of native asset to transfer to `to`. For actor calls that do not transfer funds, this is 0.

* payload (bytes)
  * Call data delivered to the target actor’s handler. The byte length is metered as Cells before VM execution begins (CIP‑3: intrinsic calldata metering).

* cycles\_limit (u64)
  * Upper bound on computational work allowed for this transaction. The VM halts with “Out of Cycles” if exceeded. Standardized and enforced to mitigate DoS (CIP‑3).

* cells\_limit (u64)
  * Upper bound on bytes that may be consumed by data events (payload, return data, storage I/O, /tmp I/O). Standardized and enforced to mitigate DoS (CIP‑3).

* max\_fee\_per\_cycle (u128)
  * Maximum price the sender is willing to pay per Cycle. Together with basefee\_cycle determines the effective payment (CIP‑3).

* max\_fee\_per\_cell (u128)
  * Maximum price the sender is willing to pay per Cell. Together with basefee\_cell determines the effective payment (CIP‑3).

* tip\_per\_cycle (u128)
  * Optional tip to block producers, per Cycle. The effective tip paid is min(tip\_per\_cycle, max\_fee\_per\_cycle − basefee\_cycle) (CIP‑3).

* tip\_per\_cell (u128)
  * Optional tip to block producers, per Cell. The effective tip paid is min(tip\_per\_cell, max\_fee\_per\_cell − basefee\_cell) (CIP‑3).

* signature (secp256k1)
  * Signature over the transaction’s signing payload. The sender address is recovered from the signature (whitepaper: EOAs controlled by secp256k1 keys).

## Validation and Execution (Informative)

* Validation: The protocol validates signature, nonce, and balance. Transactions that fail validation are rejected (whitepaper).
* Dispatch: The transaction is dispatched to `to` (EOA transfer or actor handler invocation) and enforced under all resource limits (whitepaper).
* Metering and fees (CIP‑3):
  * Cycles: Computation is metered at Python bytecode/host-call granularity.
  * Cells: Bytes are charged at I/O boundaries (intrinsic calldata, storage I/O, /tmp I/O, return data).
  * Basefee is independently adjusted for Cycles and Cells (dual EIP‑1559). The basefee portion of fees is burned; tips are paid to the producer.

## Notes

* Idempotency is achieved through nonce semantics and single inclusion in canonical block order; see Idempotency.
* Reentrancy is prevented by the actor model’s single-threaded, sequential mailbox processing and deterministic async scheduling; see Reentrancy.

## Further Reading

* [Idempotency](/architecture/tx/idempotency)
* [Reentrancy](/architecture/tx/reentrancy)
* [Fee Model Overview](/architecture/fees/overview)
* [CIP-3](/cips/cip-3)