Earth-Centered, Earth-Fixed Coordinate System (ECEF)
Learned about this after looking at REP105 for ROS Reference Frame.
ECEF is a simple Cartesian coordinate system with the center of the earth at it’s origin.
<location frame="ecef">
<x>933829.296</x>
<y>-4569502.813</y>
<z>4338267.397</z>
</location>