Woohoo! It works!

Thanks a lot. I've been trying every possible combination I could think of to get it to return what I wanted; I guess I never tried that one :-)

I don't doubt that the behaviour is exactly as it should be, only that I didn't understand it ;-)

Anyway, thanks for the solution. Would you believe I've spent nearly 2 days trying to sort this datastructure? I used to be really good at Perl (I've written big applications with large hashes of lists of lists of subroutine references etc...), but that was quite a few years ago, and now I rarely even need to use a simple unidimensional list.

Forgive me, for I have sinned...