Importing Customers & Invoices - full list of fields?

Importing Customers & Invoices - full list of fields?

Is it possible to get a full list of fields that can be used when importing customers and invoices from csvs. I cannot find a list online and the example csvs only use a few fields - I have sucesfully managed to guess a few more for customer imports etc but would appreciate a full list.

Fields of specific interest:

Customer- Contact Name, Email address, Custom Field Values

thanks