The document discusses the use of persistent identifiers (PIDs) in digital libraries to help with long-term preservation and unifying objects with their metadata. It notes that the library uses PIDs for born-digital items, digitized projects, and e-theses from across the university. While PIDs help avoid reinventing processes and ensure files don't change, the library needed PIDs that were opaque but not too opaque and long but not too long. Key points discussed include when and what gets a PID assigned, as well as different types of PID resolvers like ARK, DOI, and handles. In conclusion, the document notes that implementing PIDs is more complicated than initially thought but persistence is the most important aspect