Persistent Identifiers

A persistent identifier (PID) consists of a prefix and a postfix separated by a forward slash /. The prefix is a single number and groups one or more postfixes maintained by an institution or individual. The postfix is a unique alphanumeric string of characters. The combination of the pre- and postfix uniquely identifies a specific piece of data on a specific location by URL. An example PID is:


With a PID the actual data is not retrieved yet. To achieve this, a PID resolving service is required.

Typically, a PID does not only provide the location URL of the data the PID is referring to. In many cases additional metadata is given, for example the identifier type, owner, etc.

Resolving PIDs

The EPIC PID service provides unique persistent identifiers and allows management of the metadata accompanying the PID. To actually resolve a given PID to its corresponding location, a PID resolving service is required. For a PID registered with the EPIC PID service, the Handle service run by Corporation for National Research Initiatives (CNRI) provides these locations based on the PID. The Handle System is a comprehensive system for assigning, managing, and resolving persistent identifiers for digital objects and other resources on the Internet. The Handle System includes an open set of protocols, an identifier space, and an implementation of the protocols.

For example, to resolve the PID given above, use the Handle service proxy URL followed by the PID to obtain the actual location of the data:

leads to

Try it yourself by clicking here. The link does not provide the data, but navigates to a landing page on which the description, metadata and files of the data set are given.