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Whenever a new playlist is created via drag and drop or when a previously saved playlist is dragged from the library's "Playlists" tab to the calendar view and thus placed in the schedule, the playlist is automatically set to be a timed playlist (even if the saved playlist was a chained playlist). This is because placing a playlist in the schedule means specifying a start time which is an attribute of a timed playlist. You can change the playlist type to chained but this may mean that the playlist's start time is changed depending on the end time of the previous playlist (= the playlist's start time is changed so that the start time matches the end time of the playlist before).
Timed playlist: This kind of playlist has a predefined position and is able to attach chained playlists.
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