Well, I thought that was a closed topic. Then I ran across Article 240.30A, "Protection from physical damage". This states overcurrent devices shall be protected from damage by:
1) installation in an enclosure, ect.
2) installation on an open type switchboard, ect. free from easily ignitible material.

(I've taken the liberty to shorten the exact text some.) My point is, installation in enclosures doesn't say anything about the area around the enclosure being free from ignitible material. In addition, the handbook says "overcurrent devices enclosed in cabinets or cutout boxes ensure that hot metal particles will not be ejected in the vicinity of combustible material".

So, I'm still wondering, can a panelboard go in a closet, or not?