The work of the Joseph Haydn Institute has been well-known in eighteenth-century studies and beyond since publishing the first four volumes of the Joseph Haydn Werke in 1958. As with any Gesamtausgabe undertaking, sources occupy a central role, and with them come massive amounts of data. Naturally, compilation and organization of the metadata occurred over the life of this project, with digitization only a comparatively recent focus. Multiple factors led to the development of an idiomatic schema. Inasmuch as this system served immediate needs and created a foundation for content findability, it created limitations in accessibility, interoperability, and reusability—all desirable or essential qualities for the online Joseph Haydn Portal. It creates a distinct set of challenges for creating a digital Werkverzeichnis within the portal, the most pressing of which is transforming data into a standardized format enabled for the necessary qualities. This poster provides an overview of this process using file samples, concordances for terms and structure, and presents the challenges involved in a project of this size, and the realities of planning the project life cycle.