The document discusses extending SOA infrastructure for semantic interoperability. It discusses how SOA has limitations when it comes to semantic interoperability as current standards only provide syntactic descriptions. It introduces semantic web technologies like common vocabularies and ontologies to provide a common understanding. The Alion Semantic Mediation Bus embeds a semantic mediator in an enterprise service bus to enable runtime semantic mediation and interoperability between services with different data models and message standards based on a common ontology.