calcommands:CAL
Externally Defined Commands
rotate3dcommands:ROTATE3D
Reflects selected objects about a user-specified plane (externally defined: geom3d ObjectARX application)
(mirror3d arg1 arg2 ...)
The order, number, and type of arguments for the mirror3d function are the same as if you were entering the MIRROR3D AutoCAD command. To signify a user pressing ENTER without typing any values, use nil or an empty string ("").
T if successfu;, otherwise nil.
The following example mirrors the selected objects about the XY plane that passes through the point 0,0,5, and then deletes the old objects:
(setq ss (ssget))
(mirror3d ss "XY" '(0 0 5) "Y")