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If you wish to ensure that this attribute is considered required for a given application or for your SP in general, information needs to be added to shibboleth.xml or metadata.xml. One or more <saml:AttributeDesignator> attributes may be added to an <Application> element using the SAML attribute names to restrict the attributes available to it, while one or more <RequestedAttribute> elements in your metadata will express your desire for this data.