I checked this new command on Wings3D v2.2.1.
Other interesting things about this command...
If you union two objects whose normal is inverted, the parts touched by the objects are engraved as edges on each object.
(Edit:2019-1-30)
Coplaner is a failed case even with Boolean operation in other 3D softwares too. (See Overlapping Surface Area)
Troubleshoot_boolean_operations (Rhinoceros3D Help)
Other interesting things about this command...
If you union two objects whose normal is inverted, the parts touched by the objects are engraved as edges on each object.
(Edit:2019-1-30)
Coplaner is a failed case even with Boolean operation in other 3D softwares too. (See Overlapping Surface Area)
Troubleshoot_boolean_operations (Rhinoceros3D Help)