After you select the objects and subobjects that you want to rotate, the 3D gizmo
is displayed at the center of the selection set. The center box (or base grip) of
the gizmo sets the base point for the movement and temporarily changes the position
of the UCS while you rotate the selected objects.

You can rotate the objects freely by dragging outside the gizmo. You can also specify
an axis about which to constrain the rotation.

If you want to realign the center of rotation, you can relocate the gizmo by using
the Relocate Gizmo option on the shortcut menu.

Constrain the Rotation to an Axis

You can constrain the rotation to a specified axis. As you move the cursor over the
rotation paths on the 3D Rotate gizmo, a vector line representing the axis of rotation
is displayed. Specify an axis of rotation by clicking the rotation path when it turns
yellow.

When you drag the cursor, the selected objects and subobjects rotate about the base
point along the specified axis. The gizmo displays the degree of rotation from the
original position of the object as the object moves. You can click or enter a value
to specify the angle of the rotation.