# Adding a cross-reference lookup

## Introduction

If you have your own set of data values that you want to cross-reference, you can add your own **cross-reference lookup**. Once added, you can [use it in field mapping transformations](https://doc.wearepatchworks.com/product-documentation/process-flows/cross-reference-lookups/using-a-cross-reference-lookup-in-field-transformations).  

{% hint style="info" %}
If required, cross-reference lookups can also be updated via the Patchworks API. For more information please see our [Cross-reference lookup API ](https://doc.wearepatchworks.com/product-documentation/developer-hub/patchworks-core-api/core-api-spotlights/working-with-cross-reference-lookup-api-requests)section.
{% endhint %}

## The steps

**Step 1**\
Log into the Patchworks dashboard, then select **process flows** <mark style="color:orange;">\~</mark> **cross-reference lookups** from the left-hand navigation bar.&#x20;

**Step 2**\
Click the **create cross-reference lookup** button:

<figure><img src="https://2440044887-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FLYNcUBVQwSkOMG6KjZfz%2Fuploads%2FtAGMY7u9iAwRNK0gV51k%2Fcross%20ref%20lookup%203.png?alt=media&#x26;token=d7dbea16-6b93-445d-b58f-bc8f51756ea1" alt=""><figcaption></figcaption></figure>

**Step 3**\
Enter basic details for this lookup:

<figure><img src="https://2440044887-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FLYNcUBVQwSkOMG6KjZfz%2Fuploads%2F2Dmrm9Q1gI9nWvR73PCc%2Fcross%20ref%20lookup%204.png?alt=media&#x26;token=dcde9431-0e34-40b2-af59-8eb9f5243af4" alt=""><figcaption></figcaption></figure>

| Field       | Summary                                                                                                                                                                                                                                                                                                            |
| ----------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| Name        | Enter a name by which this lookup will be identified throughout Patchworks. Special characters are allowed.                                                                                                                                                                                                        |
| Description | Provide a bit more detail to help users understand what this lookup includes. Special characters are allowed.                                                                                                                                                                                                      |
| Default     | Set a fallback value to be used when this lookup is [used for field transformations ](https://doc.wearepatchworks.com/product-documentation/process-flows/cross-reference-lookups/accessing-cross-reference-lookups)and the associated field has a value that can't be found in the set of values for this lookup. |

**Step 4**\
Click the **create** button to confirm these details. The new lookup is created and you're ready to add your required values.

**Step 5**\
Click the **create value** button:

<div align="left"><figure><img src="https://2440044887-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FLYNcUBVQwSkOMG6KjZfz%2Fuploads%2FxN3NyV3rpDp5j1G34ojb%2Fcross%20ref%20lookup%205.png?alt=media&#x26;token=102f4f97-3780-46ea-b65b-9685d8b88d3c" alt=""><figcaption></figcaption></figure></div>

**Step 6**\
Enter details for your first value:

<figure><img src="https://2440044887-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FLYNcUBVQwSkOMG6KjZfz%2Fuploads%2FwEjuwuXfONQSwSR8Aqlw%2Fcross%20ref%20lookups%20-%20add%20value%201.png?alt=media&#x26;token=0cb1f78f-47a2-4472-8129-3572811eb6f3" alt=""><figcaption></figcaption></figure>

| Field | Summary                                                                      |
| ----- | ---------------------------------------------------------------------------- |
| Left  | Enter the 'left side' of the value mapping - i.e. the value to be converted. |
| Right | Enter the 'right side' of the value mapping - i.e. the converted value.      |

{% hint style="info" %}
You can include special characters when defining lookup values. Values do NOT need to be unique.
{% endhint %}

**Step 7**\
Click the **create** button to save this entry.

**Step 8**\
Add more values as needed.