George Marçais, an important 20th-century scholar on the architecture of the region, argues that this motif originated with the complex interlacing arches in the 10th-century extension of the Great Mosque of Cordoba by Caliph al-Hakam II.[1]:257–258 It was then miniaturized and widened into a repeating net-like pattern that can cover surfaces. This motif, in turn, had many detailed variations. One common version, called darj wa ktaf ("step and shoulder") by Moroccan craftsman, makes use of alternating straight and curved lines which cross each other on their symmetrical axes, forming a motif that looks roughly like a fleur-de-lis or palmette-like shape.[4]:232[2]:32 Another version, also commonly found on minarets in alternation with the darj wa ktaf, consists of interlacing multifoil/polylobed arches to form a more rounded lobed shape.[3]:32, 34