The DTDs and style specifications of the ISO/IEC TR 9573-11 can be processed by a number of XML/SGML tools, some of which are listed in Annex G of the TR.
An implementer of XML/SGML formatting tools reported his system at the XML Conference and Exposition 2003 of IDEAlliance held in Philadelphia, PA, US, Dec. 2003. The system was specially tuned for the style specifications defined in the ISO/IEC TR 9573-11.
The DTD of TR 9573-11 can be applied to IEC standards document as well, with a slight modification. I had an opportunity to participate in an IEC meeting, last month. At the IEC meeting I introduced the published ISO/IEC TR 9573-11 2nd edition.