X1, X2, ..., Xn

Horizontal coordinate of the cell indicated by the number of the property. X1 refers to the first cell to fill, X2 refers to the second cell to fill, and so on

Y1, Y2, ..., Yn

Vertical coordinate of the cell indicated by the number of the property. Y1 refers to the first cell to fill, Y2 refers to the second cell to fill, and so on