Learn About EZID

What is a long-term 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 persistence for two kinds of identifiers: DataCite Digital Object Identifiers (DOIs) and lower-cost Archival Resource Keys (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 are 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 are maintained.

Can DOIs and ARKs be used together?

ARK identifiers have certain features that can be very useful for:

• Keeping track of many granules of a dataset (ARKs will be able to "pass through" a suffix, so many thousands of items can be referenced on the basis of a single registration);
• Keeping track of data before a decision has been made about whether or not it is going to be retained (ARKs can be deleted).

This can make it attractive to use ARKs during the early part of a dataset's "life" or the early stages of the research process. Then, when the time comes to begin writing up results and it becomes clear which object(s) will be cited, it may appropriate to get DOIs for those objects.

DOIs have the citation-level "reputation" and it is possible to use the ARK of the cited object as the "suffix" for the DOI so that there is a traceable connection between the two. Here is what that means:

Step 1. You assign an ARK to a resource for good management and tracking: ark:/99999/fk4sf2w65j

Step 2. You decide to cite the resource, so you want a DOI.

Step 3. Using either the Advanced Create UI or the API, request a doi with this form: doi:10.5072/FK2fk4sf2w65j

In this way, the two identifiers have a relationship, so the object can be tracked throughout its life cycle. With EZID, clients get access to both of these identifiers and can take best advantage of both approaches.

What is identifier resolution?

Instead of leading directly to an object, one identifier frequently points to another, or "target URL", that 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 make this happen, 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?

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.

Who should I contact for more information?

Please contact us with any questions or comments. Also, see Identifier Basics for more information about the identifier practices implemented by the EZID team.

What is the relationship between EZID, CDL, and DataCite? And do we have to join DataCite to get DOIs?

By working with CDL and EZID, you are automatically working with DataCite, because CDL is a full DataCite member. This diagram may help explain the relationships.

After the subscription is paid, then what? How do users we want to sponsor get access?

Once the main account is set up, if you would like to sponsor other groups, then you would use the sponsored account order form to request new accounts. Please contact us for this form if you don't have it. In addition, we provide customizable outreach materials and presentations you can re-purpose to use at your institution.

Who sets up accounts for groups? Who sets up accounts for individuals?

We take care of this for you, based on the information you provide on the forms mentioned above.

We are working with a repository that is using EZID. How are the IDs issued by the repository related to EZID?

If you submit content to a repository or service working with EZID, the ARKs or DOIs it assigns come from EZID.

Can EZID identifiers be related to the links in other systems?

EZID identifiers can be related to external links if you associate them with metadata, for example by using the relatedIdentifier field in the DataCite metadata schema.

What is the best way to link to the DOIs and ARKs I create with EZID?

If you would like to include clickable links to DOIs and ARKs on a landing page, we recommend that you format them following this html template:

We discourage the practice of publishing or citing links to identifier management pages at ezid.cdlib.org because it is generally preferable for search engine crawlers to index resource (object) pages rather than pages of identifier administration details. In this way, users looking for data will be sure to find the landing pages you have prepared.

We have a DSpace repository. Is it possible (or advisable) to apply EZID identifiers retrospectively or in the future for the content in our Dspace repository?

Because EZID has an API, it is possible to write code to interact with your Dspace repository.

What happens when an account holder leaves our institution? Can he or she still update the DOI or ARK? If not, what must happen?

If an account-holder leaves your institution, please let us know so that we revoke their CREATE access to EZID. They will continue to be able to maintain all existing identifiers.

What if research partners are not at our institution? Can they also use EZID for a project partially based at our institution?

If there is a researcher from your institution associated with the project, and if you want to sponsor the access, then we are okay with extending access. Please use the sponsored account order form (see above) to request the new account.

Are we eligible to participate in your Crossref service?

As of August, 2017, only University of California clients are eligible to participate. Please contact us if you have questions about your existing Crossref service account.