One of the major research outputs of the ERC-BROKENSONG project is to create a substantial digital corpus of medieval music to support the study of musical style in medieval Britain and Ireland and the wider investigation of their medieval musical sources and repertories. A principal aim of the technical development is to create computer-based encodings of this Insular repertoire of compositions from c.1150 to c.1350, including information about both the musical content and the characteristics of the medieval notation in which the music was originally recorded. The resulting data will support computational and music-analytical research while preserving information about notation, verbal texts and other features of the original sources.