A movement back to the earlier tradition of a deity being placed on the obverse occurred in Byzantine coinage, where a head of Christ became the obverse and a head or portrait (half or full-length) of the emperor became considered the reverse. The introduction of this style in the gold coins of Justinian II from the year 695 provoked the Islamic Caliph, Abd al-Malik, who previously had copied Byzantine designs, replacing Christian symbols with Islamic equivalents, finally to develop a distinctive "Islamic style", with just lettering on both sides of their coins. This script alone style then was used on nearly all Islamic coinage until the modern period. The type of Justinian II was revived after the end of the Byzantine Iconoclasm, and with variations remained the norm until the end of the Empire. Without images, therefore, it is not always easy to tell which side will be regarded as the obverse without some knowledge.