12/19 – Flexible

"An identifier system should adjust to different requirements of different types of collections, for example it should be able to deal with varying levels of details, from individual objects to aggregations: the granularity of collections should be represented. This is called flexibility."
A PID system will work more effectively if it can handle the requirements of different types of collections.
Parts of collections may be curated at different levels of 'granularity', from parts of objects, to individual objects, to collections objects. The latter has an unbounded number of individual elements.

Organisations should use PIDs systems that are flexible enough to represent the granularity of their collections. Persistent Identifiers (PIDs): recommendations for institutions (PDF) by Gordon McKenna and Roxanne Wyns.