The Symmetry command mirrors curves and surfaces, makes the mirrored half tangent to the original, and then when the original object is edited, the mirrored half updates to match the original.
History recording must be on when the command is run.
Determines how the continuity between the mirrored objects is handled.
The mirrored curve or surface will connect to the original with G0 continuity.
The mirrored curve or surface will connect to the original with G2 continuity.
Store the connection between a command's input geometry and the result, so that when the input geometry changes, the result updates accordingly.