50 It is quite obvious that what We have said briefly here about Gregorian chant applies mainly to the Latin Roman Rite of the Church. It can also, however, be applied to a certain extent to the liturgical chants of other rites - either to those of the West, such as the Ambrosian, Gallican or Mozarabic, or to the various eastern rites.
Source: Musicae Sacrae (Vatican.va)