Cordra allots identifiers to digital objects. Such identifiers are of the form prefix/suffix (a prefix, a slash, and a suffix). Identifiers allow digital objects to reference other digital objects, and such linking can become the basis for enforcing complex business rules.

Cordra provides a built-in Identifier/Resolution Protocol (IRP) interface enabling clients to rapidly resolve digital object identifiers to their state information, or can be configured to make identifiers resolvable by registering them at external servers; see Handle Integration for details. What state information to return can be configured using Handle Minting Configuration and Create Handle Values Hook. In some communities, identifiers that are resolvable via the IRP are called handles.

Per IRP, prefixes play a special role. If a prefix is registered with credentialed parties called MPAs, then IRP clients can auto-locate the IRP provider (in this case, a given Cordra instance) and in turn auto-locate the digital objects managed by that Cordra instance wherever they are in the Internet.

Cordra APIs for creating digital objects allow users to specify the identifier (including the prefix). Admins can also specify what identifiers to use when digital objects are created with the help of Generate Object Id Hook. A single Cordra instance may have objects all with the same prefix, or may have objects of multiple different prefixes. If identifiers are not specified by users or admins, Cordra allots identifiers using a default prefix, which can be configured as indicated in Handle Minting Configuration. The default prefix (and any other prefixes used) may be registered with MPAs.