06:27 Jun 11, 2005 

Thanks for all your suggestions.
VAT number was a stupid thought of mine for a possible translation, I was sleep at the time of asking the question.
In practice the meaning of asking a lecturer who occasionally comes to the Netherlands for his sofinummer seems not to make sense, cause he/she has no Dutch sofinummer. I am curious what the legal meaning is for Non-Dutch people in this case.