The first two are the norm, I know of one cacher who uses UTMs most of the time,WGS84 stands for World Geodetic System 1984 datum.
Most countries have developed their own reference frames over time. Unfortunately each datum is slightly different. WGS84 is an agreed worldwide datum which allows people to use the same coordinate system anywhere in the world. This makes it very useful for aviation, shipping, and of course, Geocaching!
DDD° MM.mmm' - Degrees and decimal minutes - used in geocaching
UTM - Universal Transverse Mercator - UTM would be a better system to use for geocaching, because it's more accurate and, being based on the metric system, it's better suited to terrestrial applications. However, even though geocaching.com lists UTM as well as Lat/Lon, very few cachers or waypoint management programs seem to use it.
Did you set it wrong when you started?
Have you ever used other than the norm as part of a puzzle or for a change of pace?
If you see a cache by a noob with no finds do you worry about this?
WGS84 makes sense for a world wide game but why Degrees and decimal minutes?
UTMs are good for manual mapping from the GPS to a topo or street directory so why donÂ’t more people use them?
Other thoughts?