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A Server that maintains an audit log shall provide the audit log entries via Event Messages. The AuditEventType and its sub-types are defined in OPC 10000-3. An audit Event Message also includes the audit record Id. The details of the AuditEventType and its subtypes are defined in OPC 10000-5. A Server that is an aggregating Server that supports auditing shall also subscribe for audit events for all of the Servers that it is aggregating (assuming they provide auditing). The combined stream should be available from the aggregating Server.