What is a Data type of "attachments" field " base64 or Binary

I am writing this to know what is the format of the attachment field on the create ticket API. Our vendor is going to consume this API to create a new ticket. They need to know if it is a Base64 or Binary type field?

The documentation just says it’s an array of objects.

My support ticket reference: https://support.freshdesk.com/support/tickets/9741777

Thanks and Regards,
Anil Chaudhari