This is the basic data that was used to calculate the quantity of work by hand! The three lines refer to the external wall line, the center line of the external wall and the net length of the internal wall line, one side refers to the floor area! These key data in the amount of hand-calculated works, often used, such as the calculation of the area of the outer wall (including the outer frame), with the outer edge of the outer wall line, the calculation of the wall will be used (the center line of the outer wall and the inner wall of the net long line), the floor area of each floor minus the area of the wall is the ceiling and the ground area, and so on!