Hi Anthony,
The other answers already posted address your question directly.
Now for something different.
If you put a 1-d array inside a cluster, and then put that cluster inside an array, you will not have to deal with the blanks at all!
This will require an additional "bundle" when building and anothe un-bundle when un-packing, but does side-step the "rectactular" requirement of 2-d arrays.
Ben