When this method is called, an embedding of the fourfold X⊂ℙ8 in the Grassmannian Grass(1,4) is calculated and stored internally (see embed). For this step, it is required to find a rational point on the unique del Pezzo fivefold containing the fourfold. Over a finite field, the point is obtained automatically using point, but otherwise you need to pass the point using the option Point.