1. In the geomantic omen of quadrangles, the east and west wing rooms are mainly three rooms. The purpose is to create a central axis in the architectural combination of the courtyard. This line is like a person's backbone and the most important source of geomantic omen in the courtyard.
2. In the geomantic omen of quadrangles, old Beijingers never put conifers and mulberries in quadrangles.
Beijingers also taboo that the ground in the yard is lower than that in the alley and the street, because they have to "jump into the toad pit" as soon as they enter the door, which means bad luck.