Gpx WGS84 OSGB36

Hi everyone,

Im getting to grips with my new etrex 20 and making waypoints for it.

I was looking in to the GPX format and there does not seem to be anything that specifies which map datum you are using, eg. WGS84 or OSGB36.

For example: Kingshouse in Glen coe would be


How does the etrex (or any gps device) know what format the lon/lat uses? I know that the etrex can change the settings on the device to display grid refs/different coordinate systems but surely this should be specific to the gpx files espcially if you have loaded multiple gpx files using different systems?

Thanks - would appreciate any thoughts on this!

From Basic GPS Capture, Edit, and Navigation Using A Garmin GPSMAP76CSx:

I believe that this is not Garmin specific but is, in fact, part of the GPX standard.

Added later:

I have checked the GPX documentation and indeed it states:

Hm, I am also not fully sure about the datum to use. I often write the values shown in Google Earth down and then create such WayPoints in a GPX file to be transferred to my Oregon - and it works correctly! You can also set the symbol, e.g.
ArykandaFlag, Red

Thanks for the replies and for digging out that information. Good to know how the Garmins store coordinates -

It does look like that solves my problem - as the GPX docs specify that the coordinates are all WGS84 all software should interpet as such - something to check when making the files!

Thanks again,