Generally, a pass is a doorway without a door. Simply put, it has no door frame. With people's love and pursuit for the broadness and openness of space, the mouth of the mouth is more and more frequently replacing the position of the door at home. The doorway is also what we often call a door frame, which is used to fix the door leaf and protect the corner.
expansion: pass: where there are battlements. It is said that because the ancient opening and closing doors always made sounds, the mouth of the cave was converted into a dumb mouth to take its silent meaning. And Baoyakou, as its name implies, is to pack it with decorative panels.