Why light incident on the side of grating which has no ruling?

When light is incident on the side of a grating that has no rulings, there will be no diffraction pattern generated as there are no slits for the light to diffract through. Instead, the light will either reflect or transmit through the material of the grating depending on its properties such as reflectivity and transparency. The absence of rulings means that there will be no interference effects or diffraction observed as with a regular grating.