Funny, I just found this...
SEATTLE -- NS8 Corporation ("NS8Corp", the "Company") (OTCBB:NSEO) announces that it has been made aware that its shares have been listed, without its knowledge or consent, on the Berlin-Bremen Stock Exchange (the "Berlin Exchange"). The Company has sent a letter to Berliner Freiverkehr, the German brokerage firm responsible for the Company's involuntary listing, demanding that it immediately commence the application required to de-list the Company's shares from the Berlin Exchange.
It seems they do have to consent to the co stock trading there..