This NIST Internal Report contains a metadata schema for attributes that may be asserted about an individual during an online transaction. The schema can be used by relying parties to enrich access control policies, as well as during runtime evaluation of an individual’s ability to access protected resources, and for an individual’s. Attribute metadata could also create the possibility for data sharing permissions and limitations on individual data elements. There are other possible applications of attribute metadata, such as evaluation and execution of business logic in decision support systems; however the metadata contained herein is focused on supporting an organization’s risk-informed authorization policies and evaluation.