aristotle - 10:32 am on Sep 2, 2012 (gmt 0)
Also, I don't understand that reference? What do you mean by "black and white critters"?
Black and white are typical colors of pandas and penguins.
Also, a strictly "flat" structure would only have one level. A hierarchy of two levels would be less flat, etc. It's also possible to devise structures that are "mixtures" with cross-linking between different levels.