Expect to fail.
They invite ~200+ people and will only continue with the top ~20 scores. After that they'll keep widdling it with the interview/sim/psychometrics, losing about half of the candidates every time, down to the final 4 or something who get a reserve position.
Pretty much all questions are open. Draw this diagram, explain the 4 stages of blabla, what is 'insert obscure acronym here', what is an ashtam, etc. They'll also ask you to draw diagrams about things you probably will never have seen in your books, let alone remember.
They're pretty heavy handed when grading. You'll either get close to full marks, or none at all. Really very little point in guessing. If they ask for a diagram, and you don't remember it but write out the answer instead, they'll mark it as wrong.