Leggott, M., Shearer, K. & Ridsdale C. (2016). Unique Identifiers: Current Landscape and Future Trends. Research Data Canada, IDs Working Group, Standards and Interoperability Committee. 09-09-16. http://ic.idrc.ca/sites/committees/openaccess/reference/Unique%20identifiers.pdf
Persistent Identifiers (PIDs) serve two major functions: using a label or ID to uniquely identify an object, person or organization so that a reference to the entity can be unambiguous; and to provide a mechanism to locate an entity over time even when they move (persistence). A PID System adds a third function: a framework (e.g. a software and associated repository) for discovering objects described by a PID and doing something with them (such as viewing the object) and doing so in a sustainable way. The lack of PIDs, or the poor use/maintenance of them, stifles the power of discoverable or actionable information gained from linking multiple items, or objects, together – a fundamental characteristic of information systems.