So although there is an option to "split" captions, I'm finding that it doesn't always divide the caption at the position of the playhead. I've just been using the blade tool to split the caption at the exact desired location. the only downside I see is that the edit point now has the indication that it's a "thru" edit (not sure if that's the correct term, but hopefully you'll know what I mean).
Suddenly worried that I'm creating a problem that will come and bite on the butt someplace down the road.
I think just to be safe, I'll go thru and just separate the captions with at least 1 frame (since this is for a bluray, that would have to happen anyway.).
I don't really have an answer; I would also worry about some problem down line. But I did not find one in my testing. I tested PR Release 15.2 and PR Beta 15.4 Build 8. Here are my results.
I did not see the through edit indicator when razoring a caption. To razor, I targeted only the caption track. I see the through indicator on video/audio tracks if I target them.
I looked at specific frames. The ENDING timecode of a caption is NOT part of that caption segment. In the Program Monitor, if there is no caption segment starting at that timecode, you see nothing. If there is an immediately adjacent caption segment, you see the next caption text. That time code is the same whether looking in the Text Panel or the Timeline.
Methods to split a caption segment, in all methods, set the CTI to the split point: In the Text Panel, click the "Split caption" symbol. In the Timeline/Sequence, be sure the Caption Track is targeted, and use the razor tool or Ctrl-K.
Both methods result in the same timecode: the CTI time, the new end of the first part, and the new beginning of the second part.
There should be a third method, a keyboard shortcut called "Split caption segment under CTI." By default it is unmapped. I assigned it a code, but cannot get it (or its parallel, "Merge selected caption segments") to work.
There are also menu commands, Sequence -> Captions, but these two commands are not found there.