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Persistent identifiers for research data

The use of persistent identifiers (PID) is a core requisite in order to make research data accessible and fulfill the FAIR principles. The goal is to make data and metadata are easy to find, and also to make sure that it's possible to grasp the relation between research data, connected publications, authors and originators.

A persistent identifier (PID) is a type of metadata that provide a material with a unique tag that stays the same over time - even if the material has been moved to another storage solution or website.

A PID is used to make data and metadata possible to find, even when access to the actual data is restricted in any way. It is also a fast way to deduce whether similar posts in registries, catalogues or reference listings point to

  • one and the same material
  • different editions or versions
  • different materials.

PID is also used to connect research data to the resulting research articles and other related publications. They are important in order to give a coherent description of the research process behind the published results. By using a PID it is possible to connect several different publications to a data source, and thus present a coherent view on how that source has been used over time and maybe also combined with other sources of data.

Since the construction of a PID follow a predictable format, they are machine readable, that is to say, a PID can be used to connect information without human interference. 

There are several different kinds of PID. Some of the more commonly used are DOI and URN.

DOI (digital object identifier)

DOI (digital object identifier) is a widely used form of PID, that double as a link to the material. A DOI is made up of letters and numbers connected to a prefix to form a link. The DOI link is persistent and doesn't change over time.

Always include DOI when referencing a material. It is important to provide easy and direct access to the corresponding and correct information and material. As an originator it is important that you make sure that the DOI of both the published article and the data is made visible alongside other information used to reference your work. This applies to both digital and printed formats.

Each data set registered with the Swedish national data service (SND) is assigned a DOI as part of the process. DOI through SND is administered by Data Cite.

PID/DOI Service (SND)


URN (uniform resource number)

An URN (uniform resource number) is, just like a DOI, a persistent identifier awarded to digital resources in order to make sure that the resource are findable regardless of where it is currently located and stored.

URN is developed within the framework of the Internet Engineering Taskforce (IETF), who also developed internet standards such as HTTP and HTTPS.

Internet engineering task force (IETF)

PID makes research data FAIR

In order to use PID in a way that fullfill the criteria of the FAIR principles you need to

  • assign PID in machine readable formats to data descriptions, data and complimentary materials
  • assign PID in an appropriate metadata field when registering research data
  • make sure that descriptions of data always include a clear PID link to the data material.

FAIR data

Other versions of persistent identifiers

DOI and URN can also be used for articles, books and journals, in addition to other types of PID that are more format specific:

Persistent identifiers for publications and data

In addition to PID for material and publications, there are forms of PID that identify individuals, such as authors:

Persistent identifiers for researchers and authors