I also have my
Grid Square taped to my desk. A
Grid square is a series alternating pairs of letters and digits like CN89. The more characters are listed, the more precise the location, which is a good way of giving your location to any desired level of resolution and keep any level of privacy you like. With 10 characters, my grid square pretty much pin points my house, but during contests, we usually only give 4 characters, which covers an area of about 5000 km
2.