One of the operators told me he went on the system with my user name.

You can visit another member's personal channel by clicking on his or her user name.

Well, it works with the added benefit of seeing your user name when you get in.

So I tried the installation, which takes about 15 minutes, with my old user name.

Someone else, perhaps me on a forgotten previous trip, had already claimed that user name.

Each public key is bound to a user name and/or an e-mail address.

How did you know what my user name is?

The web is same as my user name, figure it out, you'll get the surprise.

No need to log in with a user name and password.

Every student is provided with his own user name and e-mail account.