structural:reformatting, information:extraction, structural:expansion
Phonology

Contrastive tones are a feature found across the family although absent in some languages like Purik. Phonation contrasts are also present among many, notably in the Lolo-Burmese group. While Benedict contended that Proto-Tibeto-Burman would have a two-tone system, Matisoff refrained from reconstructing it since tones in individual languages may have developed independently through the process of tonogenesis.