Apple Final Cut Pro 5 - Manual (Page 1309)

522 Part III Output
 The RT (real-time) pop-up menu in the Timeline: This menu only shows you options
available for the current sequence. For example, if your sequence has a timebase of
23.98 fps, and a your external video output is set to a 29.97 fps device, the RT pop-up
menu displays pull-down options. However, if you disable the external video output,
pull-down options do not appear.
You can adjust real-time playback settings in the RT pop-up menu instead of the
Playback Control tab of the System Settings window. Since the settings are identical
in both locations, it is often more convenient to use the RT pop-up menu to adjust
settings directly from the Timeline.
With very few exceptions, you can set the exact same values in either location. Usually,
it is simpler to choose your settings from the RT (real-time) pop-up menu in the
Timeline. Additional real-time playback settings can be chosen in the Render Control
tab of Sequence Settings.
Real-Time Effects
pop-up menu