Ferraz (1979: 22-24) shows that this palatal phoneme occurs typically before both oral and nasal high front vowels and the glide [y]. Since [z] typically occurs before other vowels, both phonemes are complementary in these cases. Ferraz also describes exceptions to this rule. Note further that this fricative and the voiced palato-alveolar sibilant affricate are frequently in free variation (kuji ~ kudji 'to answer', ja ~ dja 'day').