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This is a profile defining the expression of OIDC and OAuth client capabilities and characteristics in SAML 2.0 Metadata, which is the native and preferred metadata format supported by the Shibboleth IdP software.
The XML namespace for the additional content used in this profile is urn:mace:shibboleth:metadata:oidc:1.0, the schema for which can be found at http://shibboleth.net/schema/oidc/saml-metadata-ext-oidcmd.xsd
In comparison to the existing (JSON) format, all the same configuration options are available. See the table at the end for mappings between the JSON claims and the SAML metadata.
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