In Greek, the word himation means a long rectangular cloth that was worn as sleeveless garment. It was common in ancient Greece and during the middle Byzantine period. Similar to a toga, but somewhat shorter in length, it was frequently used as a garment in pictures of Christ or other biblical figures.
John of Damascus, a Greek orthodox priest and monk served as an advisor to the Muslim Caliph of Damascus in the early part of the eighth century. He referred to the Image of Edessa as a himation. From the relative safety of the Caliph’s court, he was able to criticize the Byzantine emperor, Leo III, and iconoclasm which Leo had instigated.. He wrote Apologetic Treatises against those Decrying the Holy Images, in 730, the same year that the pope excommunicated Leo.
He retells the legend of Abgar. The king, he tells us, sent envoys to obtain a likeness of Christ, a painting if necessary. Christ, who is “all knowing and all powerful" took a himation and pressed it to his face that his likeness might be on the cloth.
This is an important clue that the Image of Edessa was indeed a full-length piece of cloth.