But the only time that becomes ambiguous is if you have two speakers. Like , if you   If you only have one person , if you only have one thought that 's continuing across a particular time boundary , you just need  one arrow at each end , and if it 's picked up by a different speaker , it 's picked up by a different speaker. The time it becomes ambiguous if you have more than one speaker and that  and they sort of swap. I guess if you have more than one thread going , then you   then you need to know whether they were swapped or not.
Mm - hmm. Mm - hmm.
How often does that happen do you think ?
Mm - hmm.