The candidate is supposed to appear in "rokkostuum" (white-tie), and will be assisted by two, also in rokkostuum dressed, paranimfen. Usual these are studyfriends, but sometimes also family members. Women usually wear a dress for special occasions, for which there are no special requirements other than that it should be representative.
Leiden different
In contrast to most other Dutch universities, candidates and paranimfen in Leiden wear their rokkostuum in combination with a black instead of a white vest (and a white bow tie).