title: What, if any, checksum is used for TNT.com tracking numbers?
body: <p>I am writing some software to identify tracking numbers (in the same way that Google identifies FedEx or UPS numbers when you search for them). Most couriers use a system, such as a "weighted average mod system" which can be used to identify if a number is a valid tracking number. Does anyone know if TNT consignment numbers use such a system, and if so, what it is? I have asked TNT support, and the rep told me they do not... but I'd like to doublecheck.</p>