Okay, I've found in chapter 4 of the Book the word {kuarka}, and its type-3 version {saskrkuarka}, which it claims are valid fu'ivla. If indeed {ua} cannot occur in fu'ivla, as it cannot in lujvo, then this has to be either {ku'arka} or {ku,arka}. Which is it?
It is NOT that "ua" is not permitted in a fu'ivla (I can't specifically recall a prohibition, at least), but that it is not clear that kuarka, ku,arka, and ku'arka can be considered as *different* words because of the alternate orthography (which would be unusable if we allowed all VV's to exist in both diphthong and non-diphthong forms).
lojbab -- lojbab lojbab@lojban.org Bob LeChevalier, President, The Logical Language Group, Inc. 2904 Beau Lane, Fairfax VA 22031-1303 USA 703-385-0273 Artificial language Loglan/Lojban: http://www.lojban.org