How can I create an Empty in Blender 3D 2.73? In "Mirror changes to side of cube across all six sides", it is advised to add an Empty. However, I cannot find that option in Blender 2.73. How can I add an Empty in Blender 2.73?

When I do a Shift+A on the 3D View the context menu displays:

[Mesh||Plane|Cube|Circle|UV Sphere|Ico Sphere|Cylinder|Cone|Torus||Grid|Monkey]
Shift+A > Empty > Plain Axis



Note that you must be in Object mode for this to work, in Edit mode you may only add mesh elements.