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The <mdattr:EntityAttributes> element and the name of the SAML Attribute (urn:oasis:names:tc:SAML:attribute:assurance-certification) are defined by the OASIS specification SAML V2.0 Metadata Extension for Entity Attributes and the OASIS SAML V2.0 Identity Assurance Profiles, respectively.
A complete, working |\working metadata sample is available. To schema validate this sample metadata, you can use XmlSecTool:
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