Damasks are monochrome patterned textiles with single warps and single wefts in which the pattern weave and the ground weave have different binding systems. Twill damasks in the Shōsō-in generally have a twill (diagonal rib) weave pattern and either a twill in the opposite diagonal (i.e. a right diagonal or z-twill pattern on left diagonal or s-twill ground) or a plain-weave ground structure. Twill damasks with the same diagonal alignment but different pitch (i.e. larger z-twill on smaller z-twill) are rare in the eighth-century. When different colors are used for the warp and weft (oriiro aya), the color variations created by shifting light are greater. See also Aya.