Edited to Add: I should note that this is specific to both a map and if you are using optional facing rules, where an attack from the flank or rear is considered "flanked" regardless of the number of attackers, and attacks from the front simply are not.
Using map, but no facing, the results are different With theater of the mind, different again. It was just the diagram labels, which I was using for a playtest discussion, that were (notionally) funny.
Emoticon