Mandatory tags in GPS log files

[Juggernaut]

There are three extensions I've got - .kml , .csv  and .gpx

And a lot of software write a lot of unnecessary tags in all of these three types of GPS logs.

So what about a mandatory tags, so ExifTool will not face an error?

What are the mandatory tags for .kml file?
What are the mandatory tags for .csv file?
What are the mandatory tags for .gpx file?

[Phil Harvey]

As long as the GPS points have a latitude/longitude and timestamp then ExifTool should be able to geotag from a KML or GPX file.  ExifTool can't geotag from a CSV file.

- Phil