inline read onlyCHARACTERS:HBBufferClusterLevel = 2
inline read onlyDEFAULT:HBBufferClusterLevel = 0
inline read onlyMONOTONE_CHARACTERS:HBBufferClusterLevel = 1
inline read onlyMONOTONE_GRAPHEMES:HBBufferClusterLevel = 0