The Orthodox Church requires that all iconographers conform to an ensemble of Canons. This will guarantee a spiritual continuity and a doctrinal unity.
According to these sacred Canons, the themes of icons are traditional, canonically established and defined. The same must be said for iconographic symbolism.
In 787, the Seventh Ecumenical Council decreed:
Only the technical aspect of the work depends on the painter; its design, its disposition, its composition depends quite clearly on the Holy Fathers. (Nicea, 6a, sess.252C)