Geo fence RTL altitude

Does the RTL altitude work like RTL mode? What I’am trying to find out is,if you leave value at 0 will it return at current altitude?Any reply would be thank full.I have searched with no luck.

Yes it does work perfectly.
I just set the RTL_ALT to 1.5 meter to give me a visual indication (going up 1.5 meter before going back).
In some circumstances, I want the aircraft to go back at the same altitude, so I set RTL_ALT to 0 and the aircraft return at the same altitude.
I want the aircraft to land so RTL_ALT_FINAL set to 0.