The audit of a physical place. The land and building's form, the facing direction measured on the luopan, and the annual and monthly stars moving through each sector of the floor plan.
Read before any compass comes out. The shape of the land, what sits behind and in front of the building, roads, water, sharp corners pointing in, and the path air and people take through the entrance.
A personal system. Your birth year and gender give a gua number, and the gua sorts the eight directions into four that support you and four that do not — for sitting, sleeping and facing.
A time system. Nine stars move one palace each year, so the same room changes character annually. The wealth star is activated by use; the illness and misfortune sectors are best left quiet.
The nine palaces for a chosen year, laid out with south at the top as the classics draw them. Orient the grid to your floor plan by compass, not by the front door.
Your gua number and the four directions that support you, best first. Use them for the direction you face at a desk and the direction the crown of your head points in bed.
Eight Mansions and Flying Stars are two of several layers. A full audit also needs the building's facing degree, its construction year, and the natal star chart of the property — none of which can be read from a birth year alone.