Forgeting my pedactic nature for a while and if we want this thread to stay we should stop here......:-)

But on the other way.........:
This defines "centimetre" as a unit name that has a prefix. It doesn't fall into a distinct "prefix-unit" class. Therefore it is treated as per 9.2.
This "therefore" is wrong. From where do you conclude that? With that logic the derived units also should be treated as per 9.2. But they are not.........

Anyway i agree that there should be a discussion board for pedantic, hmmmmm no, i mean people interested at science.......... :-)