Seems to be a proposed new extention which is still pending with ICANN and IANA rather than fully operative already. Hence why many Basque language sites use .eu (like in EUskadi) as extention right now. Seems like .eus is currently battling to get accepted as a new suffix but not operative yet.
I also see .scot there ... Never understood why nobody tried to brand .sc for Scotland.
Despite living in Catalonia, I am not such a proponent of .cat, because of the precedent it created. If all minority languages would ask for new extentions... Frysia, Irish, Welsh, Scots Gaelic, Bretognese, Roma language, Kurdish language, ... probably forgetting many. If we'd all give them a proper suffix like we did with .cat, we'd get another 20 or 30 extentions. And we already got so many obscure extentions. .cat created a precedent which could lead to just another long list of obscure extentions.