Apple Final Cut Express HD - Manual (Page 492)

492 Part VII Fine-Tuning Your Edit
Clip Collision
This message appears when you try to perform an edit that might inadvertently cause
unselected clip items to overwrite others. This usually happens when you are trying to
perform a ripple edit on one track, and unselected clip items on other tracks cannot
ripple because there are other clip items in the way.
For example, suppose you are rippling a clip item on track V1 to make it 10 seconds
shorter. In a ripple edit, all clip items that occur to the right of the edit point move left
or right by the amount you are trimming. In this case, all clip items should move 10
seconds to the left to fill the gap. However, clip items in A1 and A2 cannot move to the
left by 10 seconds because there are other clip items on those tracks that are in the
way. The “clip collision” message appears.
Clip collision messages are important because they indicate that Final Cut Express HD is
making sure that clip items in your sequence aren’t accidentally overwritten. This is
especially important when you are performing ripple edits in a small portion of your
sequence and you can’t see how clip items later in your sequence are being affected.