It is not "shalln't", it is "shan't" -- https://www.dictionary.com/browse/shant
Also, you can abbreviate "it is" as "it's" and "is not" as "isn't", but what do you abbreviate "it is not" as?
Also, you can abbreviate "it is" as "it's" and "is not" as "isn't", but what do you abbreviate "it is not" as?
But hey - if Stargate uses it (and they do - S09E04) then I'm willing to count it :)