Multidimension Arrays in Types - possible ?

Really? Weird, then. I mean I sometimes complain of the lack of certain features, but the ones that are included are generally pretty well working.
But it's true that it is an undocumented feature. The real question may be why is there any undocumented feature rather than just not include anything that is fully working (as robustness seems to be the main goal of Mark, beyond the number of features).