'Man pts' and 'info pts' return nothing. 'man who' just gives the switches.
I know the info comes from the file /var/run/utmp. The contents of this are:
==> append : to filename to view the data source
And the tildes keep going.
If i append the colon, i get something that's very non-human readable.
Through Google i find that 'pts' is a Pseudo Terminal Session, and they're used for XTerm sessions. But i can't find reason for four....
I've got four desktops, which was my first thought, but i figured this would be at GUI level, and not affect the logins details.