| The gateway is monumental, with smooth jambs, a caliphal horseshoe arch with carefully cut voussoirs converging at the line of the imposts, an off-centre extrados and double-framed alfiz panel. |
| The under or concave side of the voussoirs is called the intrados, and the upper or convex side the extrados of the arch. |
| This arch was roughhewn on the flat surfaces and on about half of the outer curved surface, or extrados. |
| The form of the mound may be described as reproducing the extrados of a depressed arch. |
| The pavement of the terrace, which consists of a double bed of large bricks, rests upon the extrados of the upper channel. |
| The fitness for service analysis was based on field measurements of wall thicknesses at the extrados of the elbows. |
