One thing that you need to bear in mind is: there is no such thing as "a multi-dimensional array per se in Perl."

Instead, you have something far more powerful:   a list of references to other lists. (Hence, the various lists do not have to be of the same length.)

The “breakthrough” is this:   that “a reference to (anything)” is always “a single thing,” no matter what it refers to at any particular moment.