Invoice unique #ID (for supplier)

Why does every invoice have a #number?

As you can see across the platform, every invoice number has its own ID number. It's basically the SupplierPlus internal invoice number. 

You might have many different invoices with the same identical invoice number issued in different years. SupplierPlus invoice number or as #number will help you to distinguish these invoices. You can also use the #number in the search feature.