Intervals
This subsection specifies the minimum interval between two subtitles. This is the lowest number of frames allowed between two subtitles.
This parameter is very important. It is used by the Check Subtitles and Fix Subtitles commands: Fix Empty Out-Cues, Fix Intervals and Fix Minimum/Maximum Duration.
Durations
Minimum Duration - the min. duration in frames for a subtitle. If you have subtitles shorter than the min. duration the Checks option will report a warning.
Maximum Duration - the max. subtitle duration in frames. If you have subtitles longer than the max. duration the Checks option will report a warning.