Corresponds with the field "Billing type" / "Abrechnungsart" on the "Invoicing" / "Billing type" view of the campaign.
Use this value only if you want to explicitly define the billing type of the campaign. You can safely omit this value to let goTom apply the rules for finding the right billing type for this campaign.
Billing type possible values and their meaning:
0 - Custom - The user must explicitly set up the invoices and assign flights
1 - End / Nach Ablauf - All flights are automatically assigned to one invoice
2 - Monthly to daily value / Monatlich nach Tageswert - Automatic assignment on a monthly basis, distributed by time
3 - Monthly to delivery value / Monatlich nach Lieferwert - Automatic assignment on a monthly basis, distributed by delivery value
Please note, that your instance may not support all values. If your instance does not have an ad-server integration the value for "Monthly to delivery value" can't be used. If you use a value that is not supported by your instance, you will get an API error (code 7e44e734-3535-4172-8e32-0efa8b33a5e0) with the list of the possible values for your instance.
If the campaign has at least one invoice that has already been invoiced it is also not possible to change this value to something different. If this is the case you will get the API error code 43452cb6-8850-4036-b1f5-971c8328e10b and none of the updates in the payload will be applied.