provides user identity in transactions that cross enterprise boundaries, specifically the XDS profile that creates an Affinity Domain. When transactions cross enterprise boundaries the mechanisms found in the EUA and PWP profile are insufficient and often nonfunctional. Enterprises may choose to have their own user directory and their own unique method of authenticating. To provide accountability in these cross enterprise transactions there is a need to identify the requesting user in a way that the receiver can make access decisions and proper audit entries.