Ah, I *think* the problem is that you're parsing the words in the man
page in a completely different way from me (and, I assume, the person
who wrote the man page).  Given your new wording, it sounds to me like
there has to be an adjacent plane in each direction in order to have a
collision, which is clearly illogical.

So, perhaps your change cleared up your confusion, but only at the
expense of confusing other people.  This is not really an improvement.