The origin is the center of the earth and then a ellipse is defined using the major and minor axis. Longitudinal distances are measures west and east until they come together at the international date line 180 degrees later. For this reason we usually add a leading 0 to the east/west distances to make them 7 digits long also. To avoid negative distances in the North/South direction in the southern hemisphere always add 10,000,000 meters to this measured negative distance. For example on a cruise ship you might turn the unit on a few times each day and you will have a highly discontinuous log of your trip. Its format is two letters, two decimal digits, two letters, and can be extended for a more exact description of a location. When you first enter the user defined grid settings you will find the values for UTM already entered into the unit.
This should be done prior to taking a trip where you plan to use the tracklog to generate a return route. These new zones use a different pie shaped grid system called UPS. The southern pie is a bit larger since it needs to cover Antarctica. The GPSMAP 64s is much more sensitive and tracks better than the eTrex on cloudy days or under heavy tree cover.
Отказываясь от бумажных записей, вы не только помогаете сохранить природу, но и повышаете эффективность геокэшинга. Unlike the user defined datum however a user defined grid may or may not be successful. This information can be entered into Garmin units that support user defined datums to provide the datum of your choice.