Apple Motion 4 - Manual (Page 267)

Note: In this example, each object’s anchor point has been moved to the appropriate
axis of rotation for that object. For more information about changing an object’s anchor
point, see
Using the Adjust Anchor Point Tool .
Both arms and both legs are also made up of a hierarchy of nested body parts. It then
follows that these nested groups of layers, which connect to the torso, are themselves
nested inside the Mannequin group. When you collapse the arm and leg hierarchies, you
can see the following simplified hierarchy.
Nesting groups to
simplify a project
With all of these objects organized this way, animating the figure becomes easy. For
example, if you want to move the entire arm at once, you need only select the Left Arm
group, regardless of how many layers are nested within it.
Selecting the Left Arm
group selects all objects
within it.
267 Chapter 6 Creating and Managing Projects