The majority are now living in Vienna at state expense with another 200,000 refugees. Is it any wonder that hospitals, ...

Austrian Chancellor Sebastian Kurz called the event a "hideous terrorist attack" Four people have been killed and 23 others have been wounded in a gun attack in the Austrian capital, Vienna.

So, what is it? The Vienna Convention is the treaty that lays down the rules about treaties - legal agreements between countries. Confused by Brexit jargon? Reality Check unpacks the basics.