Right, "enclosed". This means "not open", as opposed to "not open". Please note the subtle difference, which is clearly left to the discretion of the expert (whomever that might be).
If I were possessed of infinite patience, I would make a simple remark to completely resolve this issue (yes, it's extremely simple), but those on Mt. Olympus have reserved to themselves all powers, and will not hear appeals to reason. Curious? E-mail me for the short answer.
Yes, I've long since given up trying to explain that purpose of a "rule" (official written directive, enacted before the event in question) is to anticipate and interdict subjective and extemporaneous opinions from affecting construction.
Tell the truth: aren't you happy I'm not a member, so that you don't have to suffer this abuse constantly?
Bah, humbug.