The CN Tower is at M5V2T6 - 6 chars This is unique within Canada and the physical area is small enough to be sufficiently useful for navigation. Add country co

The CN Tower is at M5V2T6 - 6 chars This is unique within Canada and the physical area is small enough to be sufficiently useful for navigation. Add country code and it gets you to 9 or 10 chars. UK has similarly useful alphanumeric postcodes and specifying them for satnav is the norm.