The Ordines Romani (Latin for Roman Orders, singular Ordo Romanus) are collections of documents that are the rubrics for various liturgical services, including the early Medieval Mass, of the Roman Rite.
The rubrics for the Mass are found in Ordo I, VII, IX-X, XV-XVII.
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.
The current critical edition of the Ordines Romani is Les ordines romani du haut moyen age (1961) edited by Michel Andrieu.