## Documentation Index

Access the complete documentation index at:
https://www.zoho.com/en-de/books/help/llms.txt

Use this file to discover all available documentation pages before proceeding.

# Retainer Invoice Preferences

Let’s have a look at the various settings you can configure for the retainer invoices module in Zoho Books.

## Field Customization

You can add multiple custom fields for the retainer invoices module and assign different data types for each of them. Learn more about [Field Customization.](https://www.zoho.com/en-de/books/help/settings/customization/custom-fields.html)

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## Custom Buttons

You can create new buttons in the retainer invoices module to perform specific actions for your transactions, or to open external links. You can create them using deluge script and execute actions based on the functions you add. Learn more about [Custom Buttons.](https://www.zoho.com/en-de/books/help/settings/customization/custom-buttons.html)