Normative and non-normative references

Is there a reason that we do not list XML Catalogs, OASIS standard 1,1?
https://www.oasis-open.org/committees/download.php/14809/xml-catalogs.html

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Best, Kris Kristen James Eberlein Chair, OASIS DITA Technical Committee Principal consultant, Eberlein Consulting www.eberleinconsulting.com +1 919 682-2290; kriseberlein (skype)