unknown (to me) extra tabs

Hi all,
In a score proposed by one of the member of this community (Vivaldi by FREDIPI) there are extra “tabs” (I don’t know what the official name is) containing each one a single voice.
Thus, beyond the “main tab” containing the whole score, there are as many “tabs” as the number of the voices playing, all part of the same file.
I’ve looked in MuseScore 2.3.2 for functions that would deal with the creation/delete of a “tab” but I could not find any that, in my eyes, would relate to them. I could not find documentation either.
Can anybody explain or provide a link to documentation that deal with this feature? Thanks.