An open source implementation of the identity metasystem conceived by Microsoft and embodied in Microsoft's CardSpace. Unlike CardSpace, which is Windows only, Higgins supports other operating systems. For example, the Higgins implementation from Parity Communications, Inc. (www.pariity.com) is a Firefox plug-in that runs on all major platforms. Novell's Bandit (www.bandit-project.org) provides client and server versions written in C++ for Mac and Linux.Enhanced Information CardsHiggins provides enhanced personal and managed cards (see identity metasystem for details). Information cards created in CardSpace can be used in Higgins, but the "z-cards" and "r-cards" created in Higgins are not currently supported in CardSpace. Both systems are in their embryonic stages, and changes in compatibility are expected as this high-level identity architecture catches on.Higgins Z-CardsThe z-card adds functionality to the managed card (m-card). It offers more privacy by caching the security token locally, and it supports subsets of claims. For example, "age greater than 21" can be delivered rather than date of birth. It also supports "zero-knowledge proofs," a cryptographic method that uses multiple iterations to prove authenticity.Higgins R-Cards (Relationship Cards)An r-card is an enhanced version of managed cards (m-cards) and personal cards (p-cards). It sets up a data synchronization relationship between the user and the relying party. A change at either side updates the other. For more information, visit www.eclipse.org/higgins. See identity metasystem and Windows CardSpace.