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

# Order cancel

> How to cancel on-chain orders on Shadowbook.

Orders can be cancelled by the user who created them. All ADA from the order - including collateral and execution fees - is returned to the user.

## Contract reference

Use the same contract details from the [on-chain orders](/on-chain-interactions/limit-order#contract-information) page:

* **Script hash:** `9e130eb0323f31df50bfbb731f35f5a795a630ef727b4ba272460b55`
* **Reference UTxO:** `2a6b847da15d7bfa3ac23af67590c2d6c98e8b485545d883dd72da322ccfd38e#0`
* **Script CBOR:** see [contract information](/on-chain-interactions/limit-order#contract-information)

## Execution units and redeemer

| Parameter       | Value                                          |
| --------------- | ---------------------------------------------- |
| Memory          | 162,000                                        |
| Steps           | 60,000,000                                     |
| Redeemer        | `Constr 0 []`                                  |
| Redeemer CBOR   | `d87980`                                       |
| Required signer | User's payment key hash from `cancellationPkh` |

## Transaction structure

**Inputs:**

1. Order UTxO to cancel
2. User's UTxO for fees

**Input (order UTxO):**

* **Redeemer:** Empty constructor `Constr 0 []` (CBOR: `d87980`)
* **Required signer:** User's payment key hash (from `cancellationPkh` in the datum)
* **Script reference:** Use the reference UTxO or attach the script CBOR directly
* **Execution units:** See table above

**Outputs:**

1. User's address with all funds from the cancelled order (including collateral)
2. User's change output (if any)

## Cancel order flow

<Steps>
  <Step title="Find order UTxO">
    Locate the order by its transaction hash and output index.
  </Step>

  <Step title="Deserialize datum">
    Extract the user's address and `cancellationPkh` from the order datum.
  </Step>

  <Step title="Add order UTxO as input">
    Include:

    * Empty redeemer: `Constr 0 []`
    * Required signer: payment key hash from `cancellationPkh`
    * Script reference or inline script
    * Execution units from contract info
  </Step>

  <Step title="Create output">
    Send full order value to the user's address.
  </Step>

  <Step title="Sign transaction">
    Sign with the user's payment key.
  </Step>
</Steps>

## Important notes

<Note>
  Only the user who created the order can cancel it - the transaction must be signed by the key corresponding to `cancellationPkh`.
</Note>

* All ADA from the order (including collateral and fees) is returned to the user
* The user's address is extracted from the datum `redeemerAddress` field
* Transaction must be signed by the key corresponding to `cancellationPkh`