(Key Mode Toggle).
Previous Frame moves the time slider back one frame.
If Key Mode is on, the time slider moves to the previous keyframe. Keyframe options are set in the Key Steps group of the Time Configuration dialog.
If Time Configuration dialog Use TrackBar is on, Previous Key jumps to the previous key of any kind. If Use TrackBar is off, Previous Key jumps to the
previous transform key, ignoring any other type of keys.