I'm studying the Magento process to pick the value from vat_id field and would like to ask you some questions to which I could not find an answer:
In the function public function getCustomerGroupIdBasedOnVatNumber($customerCountryCode, $vatValidationResult, $store = null) That is present in data.php, where are defined $customerCountryCode and $vatValidationResult? Where is Their origin?
How works Magento for take the value of the field "vat_id"?
Thanks for any help guys