Automatic numbering new Debtors / Creditors

I am missing the option new debtors and creditors do receive a unique number automatically by the program.
Maybe I am overlooking this option or else please explain how I can enable this option.

There is no automatic numbering of customers or suppliers. But you can enter an optional Code.

How can I add the option “code” into the invoice template?
Where can I find all these field codes anyway?

regards,
Jan

It is already there. Add the code when defining the customer/supplier:

If there is a code, it will appear after the customer/supplier name on invoices:

All variables are used in the standard theme (under Settings => Themes).

Thanks, I was able to add the debtor using code now.
This option can not be set to automated increasing the number?

However I am missing the answer related to my first question: when I used custom fields how do I recognize these fields on a template NOT using custom.fields (because all of them or popping up)

Kind regards,
Jan

As I said in my first response, no.

I don’t understand your second question. What do you mean about recognizing fields that aren’t used? If you check a custom field to show on documents, it will. If you don’t, it won’t.