What is Guidebook URL?

In the Edit mode of Property and Booking, there is a field called Guidebook URL.
You can set a URL in this field and use it in API Calls.
This field is also available in Inbox-> Templates through the below entities:
Booking Guidebook URL: {{ entity.guidebookUrl }}
Property Guidebook URL: {{ entity.property.guidebookUrl }}

Note: In API Calls, the system uses the Property Guidebook URL by default unless you set a link in a Booking Guidebook URL that would override the Property Guidebook URL.