How to set your GPS for different countries

In the UK we normally choose to use OSGB settings....
Our UK maps are accurate and they are overprinted with grids.

If you need to locate your position on an overseas map, you will have to use the same Coordinate System settings as (hopefully) marked on the map.
- There is a conflict between 2 and 3 and no easy answer
- If you do not use local settings for 3 then usually the error will vary from zero (common) to 100m+ (rare)
- My own experience suggests that using a GPS to locate yourself on an overseas map is a sometimes overrated pastime.
When collecting data overseas which will be subsequently shared with colleagues, one must always use the same Coordinate System. The obvious choices will be either UTM or Latitude and Longitude. Once agreed, one must always use the agreed system! When navigating such shared tracks overseas one must always set the matching setting on the GPS.
Selecting UTM will cause the GPS to select WGS84 as the Datum.
(WGS84 is not a Coordinate System: it is a datum giving precise description of the Earth's shape)

"Coordinate System" = "Grid Reference System" = "Position Format"