What is "barnett-chao"

The Barnett–Chao (abbreviated here as B–C) system of romanization for writing Cantonese is based on the principles of the Gwoyeu Romatzyh system (GR) for writing Mandarin Chinese in the Latin alphabet. The Barnett–Chao system has had a limited following and appears almost exclusively in Y.R. Chao's Cantonese Primer. There are two reasons for its lack of widespread adoption despite the inherent benefits of tonal spelling. Firstly, requires a large number of roman letters to represent each toned syllable. Secondly, like GR, it uses a complex system for representing tone that makes the system difficult to learn and obscures the basic relationship between spelling and tone.