To the bishops of the Pontic Diocese. In the title the word διοίκησις is used in its oldest ecclesiastical sense of a patriarchal jurisdiction commensurate with the civil diocese, which contained several provinces.  cf. the IXth Canon of Chalcedon, which gives an appeal from the metropolitan, the head of the province, to the exarch of the “diocese.”  “The title exarch is here applied to the primate of a group of provincial churches, as it had been used by Ibas, bishop of Edema, at his trial in 448; alluding to the ‘Eastern Council’ which had resisted the council of Ephesus, and condemned Cyril, he said, ‘I followed my exarch,’ meaning John of Antioch (Mansi vii. 237; compare Evagrius iv. 11, using ‘patriarchs’ and ‘exarchs’ synonymously).  Reference is here made not to all such prelates, but to the bishops of Ephesus, Cæsarea in Cappadocia, and Heraclea, if, as seems possible, the see of Heraclea still nominally retained its old relation to the bishop of Thrace.”  Bright, Canons of the First Four Gen. Councils, pp. 156, 157. The Pontic diocese was one of Constantine’s thirteen civil divisions.