Apple Final Cut Pro 5 - Manual (Page 1415)

64 Part I Media and Project Management
About the Connections Between Clips and Media Files
Final Cut Pro is very flexible about the connection between clips and their media files.
It is fairly easy to make a clip go offline by accidentally moving or modifying a media
file in the Finder, but it is also very easy to reconnect clips to media files.
A clip connects to a media file via the clip’s Source property, which contains the
location of the media file as a file path. If a clip cannot locate its media file, the media
file is considered offline, and the clip is called an offline clip. An offline clip has a red
slash through its icon in the Browser:
Each time you move from Final Cut Pro to another application and then back again,
Final Cut Pro checks that the modification date of each clip’s media file has not
changed, and that they are in the expected file path. If a media file has been modified,
Final Cut Pro warns you that the media file has gone offline, and asks if you’d like to
reconnect the clip. You can choose to do this immediately, or you can do it later. If you
don’t successfully reconnect clips to their media files, the clips remain offline.
These are offline clips.