Handbook of Liturgical Practice of the Russian Church Abroad
For a monastic who has attained the rank of Ryassofor or higher, it is expected that he, like all members of the white clergy, will never appear in the temple in his cassock alone, but wearing also his ryassa over it. When the monk attains the rank of the Little Schema and is given the mantia, he also wears this in the temple as is appointed by the ustav of his monastery (in some monasteries, all mantia monks wear their mantia whenever they are in the temple; in others, they wear the mantia only when they are, by obedience, serving or fulfilling a specific ecclesiastical function at that service — e.g. leading the kliros, serving as canonarch — with the others in ryassas without mantia).
Technically speaking, the mantia is worn over the ryassa, which is itself worn over the cassock. However, it is a widespread economia in most of the monasteries of our Church Abroad that, when the mantia is worn, the ryassa may be set aside beforehand so that the mantia is worn directly over the cassock (this is helpful, for example, in monasteries set in hot climates; or when a monk is given the obedience to serve in a particular role — e.g. candle-lighter — where the broad sleeves of the ryassa, which can catch against the mantia, might pose a difficulty to dignified service).
Illustration: A photograph showing (at left) a monk who is wearing his mantita over his ryassa, as is the full practice.
This is a matter that is to be determined by the superior of the monastery. When a monk is, with a blessing, sent out to a parish, he should assume that the fuller dress (cassock, ryassa and mantia together) is the norm there, unless informed otherwise by the Diocesan Bishop or Parish Rector.