Apple Final Cut Pro 7 - Manual (Page 800)

About Changing the Duration of Nested Sequences
When you first nest a sequence into another sequence (sometimes known as the parent
sequence), changes in the original nested sequence that affect its duration are reflected
in the parent sequence. For example, if you shorten a clip in the original nested sequence,
the overall sequence duration changes. As a result, the duration of the nested sequence
within the parent sequence is also shortened, and the subsequent clips in the parent
sequence are rippled to compensate for the shorter nested sequence.
This is quite helpful, since otherwise you’d end up with gaps in your parent sequence
whenever you change the length of one of your nested sequences. This is convenient
when each of your movie scenes is in a separate sequence. After you’ve edited all your
scenes together, if you decide to reedit any of the scene sequences, the changes you
make will automatically ripple items in the entire master sequence.
For example, suppose sequence B, which has a duration of 10 seconds, is nested inside
another sequence, with more clips appearing to the right of it.
Nested sequence B
inside another sequence
You open sequence B and add two more clips to the end of it, extending its duration
from 10 to 15 seconds. Once you’ve done this, all of the clips in the parent sequence that
are to the right of the nested sequence B are automatically rippled 5 seconds to the right
to accommodate the lengthening of the nested sequence B.
Adding clips to sequence B
ripples the parent sequence.
800 Chapter 49 Sequence-to-Sequence Editing