Get number on current invoice

If I look at the list of invoices in e-conomic, the first column is called "Nr.".

However, if I get the list via the api CurrenctInvoices_GetAll(), and then CurrentInvoce_GetDataArray, I can't find this number anywhere.

Each currentinvoice just has an Id, which is not the same number as shown in the list in e-conomic.

Is there a way to get the "real" invoice no. instead of this Id?

 

BR. Kenneth Johnsen.