|In some older transcripts (cited in some papers you will read), a double slash indicates the point at which a current speaker's utterance is overlapped by the talk of another, which appears on the next line attributed to another speaker. If there is more than one double slash in an utterance, then the second indicates where the second overlap begins, the overlapping talk appearing on the next line attributed to another speaker, etc. In transcripts using the // notation for overlap onset, the end of the overlap may be marked by a right bracket (as above) or by an asterisk.|
So, the following are alternative ways of representing the same event:
Bee's "Uh really?" overlaps Ava's talk starting at "a" and
ending at the "t" of "tough."