Probe results - possible results from a probe query.

xplm_ProbeHitTerrain"0" The probe hit terrain and returned valid values.
xplm_ProbeError"1" An error in the API call. Either the probe struct size is bad, or the probe is invalid or the type is mismatched for the specific query call.
xplm_ProbeMissed"2" The probe call succeeded but there is no terrain under this point (perhaps it is off the side of the planet?)