MirrorMirror a pattern/element or group of patterns/elements which have been marked for manipulation.
Make your choices from the following dialogue box

Selection Keep will retain the original selected entities.
Discard option will delete the original selected entities.
Mark the pattern(s) or element(s) to scale using the MARK sub-menu commands if the Auto Clear switch is on. (Patterns/elements can be marked at any time when the Auto Clear switch is off.) After pattern(s) or element(s) have been identified for manipulation, enter the point about which to mirror and the mirror angle. A negative angle is clockwise and a positive angle is anti-clockwise.
You can use the & commands (&scale, &rotate and &mirror) at any time during this command.
All transformation and manipulation commands.
All the mark and unmark commands.
Standard Selection