Apple Final Cut Pro 6 - Manual (Page 561)

228 Part II Rough Editing
If you select just the audio and move it out of sync, out-of-sync indicators appear.
The Mark in Sync command permanently affects the sync relationship of the selected
clip items in your sequence. Once you’ve modified the sync relationship of clip items,
the only way to restore the original sync relationship is to manually move the clip items
into the old sync relationship and use the Mark in Sync command again, or to delete
the clip items and reedit a new instance of that clip into your sequence from
the Browser.
Learning About Linking Behavior in Audio Channel Pairs
In addition to linking video or audio clip items together, you can also link pairs of audio
items together in stereo pairs. Stereo linking is a specific kind of audio item linking,
limited to two audio clip items that are parallel in the Timeline.
Stereo pairs allow you to control audio levels, pan settings, and effects for two audio
items at once. Any modifications made to one item in the pair affect the other item. This
is convenient when you are working with audio such as music, stereo sound effects, or
any other audio recorded in stereo. One item of a stereo pair cannot be selected
separately, even if you turn off linked selection using the Linked Selection button.
For more information about stereo audio, see Volume III, Chapter 1, “Audio Fundamentals.”
The out-of-sync indicators
show the new offset, not
the original offset.