I view clefs the same way you do: three types and a set of rules. Who says there are only nine? There are lots more possibilities than that, but why on earth would one catalogue them?
On reading but not writing: as with any other language, parsing is easier than generation for most people. Just tonight this really struck me when someone asked me, in Hebrew, if I speak Hebrew, and while I understood perfectly what he had said, I was unable to formulate a proper reply. (I ended up saying "katan", which actually means "small", because I don't know how one would render "a little". I was working on "I understand (some) but don't speak", but couldn't conjure up the word for "understand". And so it goes. (Yes, I realize that technically, had I formed that response, it would have been a mis-statement, but I would have relied on the slow pidgin-Hebrew formulation to convey the reality. :-) ) )
(no subject)
On reading but not writing: as with any other language, parsing is easier than generation for most people. Just tonight this really struck me when someone asked me, in Hebrew, if I speak Hebrew, and while I understood perfectly what he had said, I was unable to formulate a proper reply. (I ended up saying "katan", which actually means "small", because I don't know how one would render "a little". I was working on "I understand (some) but don't speak", but couldn't conjure up the word for "understand". And so it goes. (Yes, I realize that technically, had I formed that response, it would have been a mis-statement, but I would have relied on the slow pidgin-Hebrew formulation to convey the reality. :-) ) )