Apple Final Cut Express 4 - Manual (Page 315)

Chapter 23 Setting Edit Points for Clips and Sequences 315
VI
Things to Keep in Mind When Setting an Out Point
When you want to mark the duration of a clip in a sequence, you need to remember to
set the Out point one frame earlier than you might expect, or you may also include the
first frame of the next clip. This often happens when you have snapping turned on and
you snap to clip start and end points to set In and Out points.
For example, suppose a clip in the Timeline is a shot of a playground and the next clip
is a shot of a classroom. When you move the playhead to snap to the end of the
playground clip, you see the first frame of the classroom clip in the Canvas. If you then
set an Out point and copy and paste the playground clip, you see one classroom frame
at the end of the pasted content. You probably didn’t intend to include the first frame
of the classroom shot, but it was included because of the Out point inclusive rule.
The Out point includes
the first frame of the
adjacent clip.