Hi qabi,
You shouldn't use the VatZone property anymore. This is only in the API for backwards compatibility.
You should use the ExtendedVatZone. You can find the different ExtendedVatZones by calling https://api.e-conomic.com/secure/api1/EconomicWebService.asmx?op=ExtendedVatZone_GetAll and then https://api.e-conomic.com/secure/api1/EconomicWebService.asmx?op=ExtendedVatZone_GetDataArray
Handles are strongly typed ids. So a handle is in essense a reference to another entity in the API.
Values you don't need can be omited.
Best regards