To drag the ranges and linked descendants of an object:
Modify Subtree is on by default.
With Modify Subtree on, a range bar is displayed in the Objects branch. The Objects branch is the default parent of all named objects in the scene.
Dragging a parent Objects range bar with Modify Subtree on affects all tracks subordinate to the object and all tracks of its linked descendants.
Dragging the World range bar with Modify Subtree on affects all tracks in the scene, including Sounds, Materials, and all tracks of all objects.
The World range bar and the Objects range bar are no longer available. In this mode you can affect the range of an individual object or track without affecting its descendants.
Edits (cuts, pastes, or moves) keys in the parent track. Anything you do to the keys in the parental track affects the child keys as well.
Affects the tracks of an object and all of its descendent objects. When you edit the range of a parent object, the child objects are also affected.