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While not all that common, the attribute-filter.xml file can leverage property replacement to externalize particular settings. By default, these properties are defined in the idp.properties file. Properties are referenced via a brace syntax (e.g., %{idp.home}).
The properties which affect the filtering process are names staring with idp.service.attribute.filter as described here
Schema Name
Elements described in this page and its children are defined by the urn:mace:shibboleth:2.0:afp namespace, the schema for which can be located at http://shibboleth.net/schema/idp/shibboleth-afp.xsd
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