Слово встречается в следующем контексте:
The next tier above that contains Icons of those Saints closest to the Savior, usually the Holy Apostles. Just above the Icon of the Last Supper is placed an Icon of the Savior in royal garments, flanked by His Mother and St. John the Baptist, called the Deisis (prayer), since the Theotokos and the Forerunner are turned to Him in supplication. As these Icons (Apostles, Theotokos, and Forerunner) are arranged in order on either side of the Savior the tier is usually called the Tchin (or rank). Often this tier was to be found just above the Local Icons and below the Feast Day Icons.

Заранее спасибо.