It is controversial. The straight columns and horizontal sills come from "Afang Palace Fu". Its correct pronunciation is controversial. In traditional understanding, "rail" and "sill" both mean railings, expressing straight and horizontal railings. But the teachers’ teachers have taught in this way before, and if they continue to teach according to their mature experience in the past, they have a sense of inheritance, which is quite sacred. In addition, if it is read as "kǎn", "straight railings and horizontal thresholds" is interpreted as "straight railings and horizontal thresholds", resulting in incongruity between sentence groups.