Apple Motion 4 - Manual (Page 268)

When you rotate the selection in the Canvas, every object nested within that group rotates
as a single item.
Before rotating Left Arm group After rotating Left Arm group
Another example of how you might make use of the group hierarchy can be seen through
the application of filters and behaviors. If you apply a filter to a single layer within a group,
the filter affects only that layer. All other layers within the group remain unaffected.
Filter applied to a single layer
268 Chapter 6 Creating and Managing Projects