Understanding identifiers

What is a persistent identifier?

An identifier is an association between a character string and an object. Objects can be files, parts of files, names of persons or organizations, abstractions, etc. Objects can be online or offline. Character strings include URLs, serial numbers, names addresses, etc. A "persistent identifier" is an identifier that is available and managed over time; it will not change if the item is moved or renamed. This means that an item can be reliably referenced for future access by humans and software. EZID currently supports persistent for two kinds of identifiers: DataCite DOIs and lower-cost ARKs.

What is a DOI?

DOI stands for "Digital Object Identifier." It is an identifier originating from the publishing world and in widespread use for journal articles. DOIs become persistent when the objects and identifier forwarding information is maintained.

What is an ARK?

ARK stands for "Archival Resource Key." It is an identifier originating from the library, archive and museum community. ARKs become persistent when the objects and identifier forwarding information is maintained.

What is identifier resolution?

Instead of leading directly to an object, one identifier frequently stands in for another, or "target URL", that itself leads directly to the object. The process of getting to the final target name, possibly via a chain of intermediate names, is called "resolution". Resolution on the web is usually fast and invisible. It is done behind the scenes on your behalf by web browsers. Unsuccessful resolution, however, usually means visible failure to access the object that you were expecting, resulting in a "broken identifier." Objects tend to move, so identifier persistence depends on resolution using up-to-date target URLs. To this end, EZID provides a way for people to update target URLs as they change when objects move around. This is very similar to leaving a forwarding address when you change your residence. As the starting point for resolution, the resolver effectively lets you publicize an unchanging identifier that you maintain so that it will consistently hit a target that may be moving. EZID currently updates two resolvers: N2T (Name-to-Thing) based at n2t.net and the DOI (Digital Object Identifier) resolver based at doi.dx.org.

What is metadata entry?

Metadata is information (data) about the object, such as the name of the object's creator, the date of creation, the target URL, the version of the object, its title, and so on. EZID allows the user to enter metadata at the same time as an identifier is requested. Associating metadata with identifiers enables more sophisticated mechanisms for digital content discovery and higher-level assurances of long-term persistence.

What is object deposit?

We mean by this term that EZID will serve as the an optional front end to a managed repository, such as UC3's Merritt Repository.

Who should I contact for more information?

Please contact us with any questions or comments.