Identifying PIDs playing FAIR

This is an extended, revised version of Philipson ( 2017 ). Findability and interoperability of some PIDs, Persistent Identifers, and their compliance with the FAIR data principles are explored, where ARKs, Archival Reource Keys, were added in this version. It is suggested that the wide distribution and findability (e.g. by simple ‘googling’) on the internet may be as important for the usefulness of PIDs as the resolvability of PID URIs – Uniform Resource Identifiers. This version also includes new reasoning about why sometimes PIDs such as DOIs, Digital Object Identifiers, are not used in citations. The prevalence of phenomena such as link rot implies that URIs cannot always be trusted to be persistently resolvable. By contrast, the well distributed, but seldom directly resolvable ISBN, International Standard Book Number, has proved remarkably resilient, with far-reaching persistence, inherent structural meaning and good validatability, through fixed string-length, pattern-recognition, restricted character set and check digit. Examples of regular expressions used for validation of PIDs are supplied or referenced. The suggestion to add context and meaning to PIDs, making them “iden