Persistent identifiers for digital objects

Persistent Identifiers (PI or persistent digital identifiers) are long-lasting, unique, numeric and/or character strings that reference a digital object such as a file or a set of files. They facilitate access to the digital object via a persistent link.

Digital Object Identifiers (DOI) are one example of persistent identifiers. The DOI system enables the registration and use of persistent interoperable identifiers, called DOIs, for use on digital networks. Clicking on a DOI directs the user to one or more URLs or other services related to a single resource. If the URLs or services change (for example if the resource moves) the DOI continues to direct users to the correct resources or services at their new locations.

The allocation of ISBN numbers (International Standards Book Numbers) to publications is another example of a persistent identifier.

It is thought that the use of persistent identifiers could be useful in Building Information Modelling (BIM). BIM is a very broad term that describes the process of creating and managing a digital model of a building or other facility (such as a bridge, highway, tunnel and so on).

If a unique identifier were allocated to each individual building component, it might:

Avoid the need for different identification systems throughout the supply chain.
Allow product details to be accessed reliably in the future for maintenance and replacement purposes.
Give a more accurate method of referring to components.
Help digitise whole assets such as buildings.
Act as a form of meta-data, for information from manufacturers' catalogues and other sources.

The identifier could be applied to every individual item, specific batches, or classes of items. It might take the form of a barcode, a radio transmitter or some other form of physical marker.

In October 2015, RIBA Enterprises, the British Standards Institution (BSI) and the Construction Products Association (CPA) announced a 2-year project, supported by a grant from Innovate UK, to research the use of persistent identifiers for buildings. If the research is successful, a joint venture may be established to manage the scheme.

James Forbes, project manager at RIBA Enterprises, said “A product is manufactured, it goes to a distribution centre, then it goes to a trade company or builder's merchant, and at each step it's pushed into a different system and classified in a different way. If you have a persistent identifier you can trace everything back to its origin.”

“If you have a building that's 30-odd years old and on each floor you need to replace some doors, you could look at the reference code for that door, you could see that it was made by a company in Germany that no longer trades – but the code would tell you what alternative you could use. So, if it was a fire door it would have the same properties and dimensions, and so on.”