When you build an AoA, you're just building an array, who's values are references to other arrays. So while you write:

@a = (
       [ qw/1 2 3/ ],
       [ qw/a b c/ ]
     );
[download]

You're actually creating 3 arrays, and put in @a references to the other two.

So when you pass that to a sub, it's passed as a simple list - but the members of the list are still the references to your two arrays, and perl doesn't really care if they're scalars or references - there's no automatic-recursive-dereferencing going on...

Does that help at all?

-- zigdon