Apple Final Cut Pro 5 - Manual (Page 559)

224 Part II Rough Editing
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.
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.
A mixed-sync indicator
Out-of-sync indicators