>not an open specification (but then what from Microsoft is)

RTF
http://msdn.microsoft.com/library/en-us/dnrtfspec/html/rtfspec.asp

Includes code samples; this is the format that is used by all Word
import/export operations (including HTML).

 XSL-List info and archive:  http://www.mulberrytech.com/xsl/xsl-list