SEPA Direct Debit Mandate Creation Questions

Hi ,

I want to create a direct debit mandate (E 9.1) for use in SEPA , under the Creditor Tab , scheme identification there are 4 boxes , the first one is for the 'country code' which is self explanatory , the second is a 'verification digit' , can anybody tell me how to calculate this please  ?, the third is 'business code' which you can populate with zzz if you are not using this , how do you know if you are using it or not ? , the final box is for the national Id , is this the 'Tax Id' ?  thanks for looking at this

Regards

SD