The file name is 230114.pdf (DDMMYY, 23 January 2014). This is what it looks like when stored in a folder:

A bit hard to find an invoice by name (yes, could sort by date but that's not the point).
To make it easier to find invoices, it would be logical to actually have the file name as YYMMD.pdf instead. This way everything would be automatically order.
Easy to do, right?