Implementing Persistent Identifiers

This document, by Hans-Werner Hilse and Jochen Kothe in November 2006, is a fairly complete reference to key issues on Persistent identifiers. It discusses various types of identifiers including Handles, Digital Object Identifiers (DOIs), Archival Resource Keys (ARKs), Persistent Uniform Resource Locators (PURLs), Uniform Resource Names (URNs), National Bibliography Numbers (NBNs), and the OpenURLs. Examples and references are provided for each type of identifier.