XRI (Extensible Resource Identifiers), adds new features to URIs and IRIs that are especially useful for digital identity systems. OpenID also supports XRIs, and XRIs are the basis for i-names. Risk-based authentication Risk-based authentication is an application of digital identity whereby multiple entity relationship from the device (e.g., operating system), environment (e.g., DNS Server) and data entered by a user for any given transaction is evaluated for correlation with events from known behaviors for the same identity. Analysis are performed based on quantifiable metrics, such as transaction velocity, locale settings (or attempts to obfuscate), and user-input data (such as ship-to address). Correlation and deviation are mapped to tolerances and scored, then aggregated across multiple entities to compute a transaction risk-score, which assess the risk posed to an organization. Policy aspects There are proponents of treating self-determination and freedom of expression of digital identity as a new human right. Some have speculated that digital identities could become a new form of legal entity. Taxonomies of identity Digital identity attributes exist within the context of ontologies. The development of digital identity network solutions that can interoperate taxonomically diverse representations of digital identity is a contemporary challenge. Free-tagging has emerged recently as an effective way of circumventing this challenge (to date, primarily with application to the identity of digital entities such as bookmarks and photos) by effectively flattening identity attributes into a single, unstructured layer. However, the organic integration of the benefits of both structured and fluid approaches to identity attribute management remains elusive. Networked identity Identity relationships within a digital network may include multiple identity entities. However, in a decentralized network like the Internet, such extended identity relationships effectively requires both the existence of independent trust relationships between each pair of entities in the relationship and a means of reliably integrating the paired relationships into larger relational units. And if identity relationships are to reach beyond the context of a single, federated ontology of identity (see Taxonomies of identity above), identity attributes must somehow be matched across diverse ontologies. The development of network approaches that can embody such integrated "compound" trust relationships is currently a topic of much debate in the blogosphere. Integrated compound trust relationships allow, for example, entity A to accept an assertion or claim about entity B by entity C. C thus vouches for an aspect of B's identity to A. A key feature of "compound" trust relationships is