... supports persistent identity identifiers. OYSTER is unique among other ER systems in that it is built to incorporate Entity Identity Information Management (EIIM). OYSTER supports EIIM by providing methods that enforce identifiers to be unique among identities, maintain persistent IDs over the life of an identity, and allowing the ability to fix false-positive and false-negative resolutions, which cannot be done with matching rules, through the use of assertion, traceability, and other features.