Trimble can operate in a 3D positioning operation mode that works that way. But their "overdetermined clock" mode is what most people call "position hold" mode. Set the receiver to "overdetermined clock", and the lat/lon/alt coordinates it sends never change. ------------------------ As far as I know, it simply means that there are more satellites in view than needed for a fully accurate time to be determined. If it needs four sats to come up with a valid location plus time, it has five or more.