my understanding is they dont have a straight pass mark as you have asked. I do believed they get all papers marked then have a look at how all have done and then deside how many percent get passed out of the test papers done. I may be wrong but also if you google the Chief examiners report for 2391 exams you will get all pevious results and reviews of the tests done before. I think I had to wait about 12 weeks to find out and the report to go online, hope this helps and good luck with you results. I think the test I done a few years ago only 36% of test papers got passed.