In Chaha the impersonal and Sg. 3m. object suffixes labialize the
nearest preceding plain noncoronal consonant. Furthermore a consonant
will become identical to the next following consonant if it can do so by
becoming labialized or palatalized. An attempt to formulate these rules
in an economical way that reflects universal constraints on action at a
distance leads to the proposal that the notation Xo be abolished from
generative phonology and that in its stead there be used structural
descriptions of the more restricted for [X [Y] [Z] ], having the
meaning of [X, Y][-X]0 [X, Z] .