Persistent identifiers for research data

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

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

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

A PID is also used to connect research data to the resulting research articles and other related publications. They are important to provide 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 thereby present a coherent view of how the source has been used over time and also how it may have been combined with other data sources.

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

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

DOI (digital object identifier)

A DOI (digital object identifier) is a widely used form of PID that doubles as a link to the material. A DOI consists of letters and numbers connected to a prefix to form a link. The DOI link is persistent and does not change over time.

Always include a DOI when referencing material. It is important to provide easy and direct access to the corresponding and correct information and material. As an originator it is important to ensure 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. A DOI through the SND is administered by Data Cite.

PID/DOI Service (SND)

Data Cite

URN (uniform resource number)

A URN (uniform resource number), like a DOI, is a persistent identifier allocated to digital resources to ensure that they are findable regardless of where they are currently located and stored.

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

Internet Engineering Task Force (IETF)

A PID makes research data FAIR

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

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

FAIR data

Other versions of persistent identifiers

Persistent identifiers for researchers and authors

Making sure that you as a researcher are always possible to connect to your publications.

Persistent identifiers for publications

Making sure that your publications can be found and identified in the long term.