The Ordines Romani are collections of documents that are the rubrics for various liturgical services, including the early Medieval Mass, of the Roman Rite

Roman Rite

The Roman Rite is the liturgical rite used in the Diocese of Rome in the Catholic Church. It is by far the most widespread of the Latin liturgical rites used within the Western or Latin autonomous particular Church, the particular Church that itself is also called the Latin Rite, and that is one of...

. There are about 50 recognized Ordines Romani (singular: Ordo Romanus).

They span many centuries throughout the Middle Ages

Middle Ages

The Middle Ages is a periodization of European history from the 5th century to the 15th century. The Middle Ages follows the fall of the Western Roman Empire in 476 and precedes the Early Modern Era. It is the middle period of a three-period division of Western history: Classic, Medieval and Modern...

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The rubrics for the Mass

Mass

Mass can be defined as a quantitive measure of the resistance an object has to change in its velocity.In physics, mass commonly refers to any of the following three properties of matter, which have been shown experimentally to be equivalent:...

 are found in Ordo I, VII, IX-X, XV-XVII.

Those for Baptism

Baptism

In Christianity, baptism is for the majority the rite of admission , almost invariably with the use of water, into the Christian Church generally and also membership of a particular church tradition...

 are found in Ordo XI, XXII-XXIV and XXV.

Those for Ordination

Ordination

In general religious use, ordination is the process by which individuals are consecrated, that is, set apart as clergy to perform various religious rites and ceremonies. The process and ceremonies of ordination itself varies by religion and denomination. One who is in preparation for, or who is...

 are found in Ordo XXXIV-XXXV, and XXXIX.

Those for Funeral

Funeral

A funeral is a ceremony for celebrating, sanctifying, or remembering the life of a person who has died. Funerary customs comprise the complex of beliefs and practices used by a culture to remember the dead, from interment itself, to various monuments, prayers, and rituals undertaken in their honor...

s are found in Ordo XLIV.

Finally, those provisions that deal with the Dedications of Churches are found in Ordo XLI-XLIII.

The oldest is Ordo XI which is from around AD 650 and concerns Baptism

Baptism

In Christianity, baptism is for the majority the rite of admission , almost invariably with the use of water, into the Christian Church generally and also membership of a particular church tradition...

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The current critical edition of the Ordines Romani is Les ordines romani du haut moyen age (1961) edited by Michel Andrieu.