jm lØæÇQÞÖ¹~û9´#¹Zæ|ÜFûl5äNLFrom what I can tell, a special escrow TX is created. This TX has special properties in that once it's created, there are only a few actions that can be taken.
https://whatsonchain.com/tx/e60ed48429b4151d38c997da4169388c0e36e5945f94b04d262701fcd07cd151