A Koreferat is an evaluation of a PhD thesis. It should be written in the style of a review. The following points are extremely important:
You should consider the following aspects in your review (and possibly others):
Your review should justify the grade assigned. The on-line instructions state that 6 = Outstanding, 5.5 = Very good, 5 = Good, 4.5 = Satisfactory, 4 = Sufficient (pass). You should take this literally. I would hope that most theses merit a Good, though this may not always be the case. Probably many (not all) will be Very good. Please save a 6 for a truly Outstanding Work. There are two grades for the thesis (one from the supervisor and one from the Koreferent). There is also a grade for the defense itself, decided by the examination committee. This is generally the last chance to raise or lower the grade depending on factors that may not have been taken into account in the review of the thesis itself.
Please send the scanned review directly to Oscar by email, before the deadline.
The web site of the Faculty of Science provides guidelines for completing the review. I would not recommend using these directly for completing your review, but you can refer to them if you find them useful:
I suggest instead writing a normal evaluation on your official letterhead that summarizes and assesses the thesis, covering some of the points listed in the form above, and concluding with the final grade.
See also: How to apply for your PhD defense
Oscar Nierstrasz 2005-09-30, updated 2012-08-29, 2012-09-20, 2016-01-20