This document is the third of the five interrelated reports of the Radioactive Waste Repository Metadata Management (RepMet) Initiative. The series of reports discusses the key aspects of data and related metadata for selected scientific and technical topics involved in the life cycle of a radioactive waste repository. The "Waste Package Library" report supports an associated technical library dealing with data and related metadata about packaged waste and spent nuclear fuel that, after proper treatment and conditioning processes, are ready for final disposal at the repository.