nic.ch is in the ch zone itself. So it's not a zone of its own.
You will find it in whois so that people see that it's not available anymore.
Thanks. I suspected something like that, so I compared this to other ccTLDs and it's different there, e.g. for nic.fr and denic.de you get NS records:
dig @ns1.denic.de denic.de ns dig @ns1.nic.fr nic.fr ns
Why is this different for nic.ch?
Daniel