That line splits the horoscope into two sectors: the eastern hemisphere on the left and the western hemisphere on the right.
Now, divide your chart in half vertically or along the meridian, which runs from your midheaven, or M.C., at the twelve o’clock spot on your chart to your I.C. at the six o’clock spot. That line splits the horoscope into two sectors: the eastern hemisphere on the left and the western hemisphere on the right.