Apple Final Cut Pro 7 - Manual (Page 708)

Holding down the Command key while selecting an edit point allows you to add edit
points to the current selection without deselecting previously selected edit points.
Current Out point of
outgoing video clip
In point of incoming
audio clips
Intended video
edit point
Before
4 Use the Ripple tool to trim the above selection.
The video and audio edit points move in opposite directions, creating a split edit.
Audio/video synchronization is maintained in both clips.
This clip remains
the same length. Incoming audio clip
is trimmed shorter
from its In point.
Outgoing video clip
is trimmed shorter
from its Out point.
This clip remains
the same length.
After
708 Chapter 44 Performing Slip, Slide, Ripple, and Roll Edits