Apple Final Cut Pro 7 - Manual (Page 594)

If you then move a second pair of audio items out of sync by a different amount, each
audio item that is out of sync from the anchor item has an out-of-sync indicator noting
its individual offset from the anchor item—in this example, the video item. The anchor
item displays a mixed-sync indicator with no duration. This tells you that multiple linked
items are out of sync by varying amounts.
A mixed-sync indicator
Out-of-sync indicators
Linking and Unlinking Video and Audio Clip Items in the
Timeline
You can link additional clip items to already linked items, or remove items and then relink
the remaining items.
Linking Video and Audio Clip Items
When you link clip items, a sync relationship is established between those items, according
to their position in the Timeline. All linked clip items are marked in sync, and this new
sync relationship is tracked.
594 Chapter 40 Linking and Editing Video and Audio in Sync