Set the following options to values appropriate for DocBook:
; UseDOCTYPE = Yes (default) or No (when writing DocBook entity files)
; UseXMLRoot = Yes (default) or No (when writing DocBook entity files)
; XHLangAttr = xml:lang (default, set as needed)
When [DocBookOptions]WriteBookFile=Yes, Mif2Go sets UseDOCTYPE and UseXMLRoot to No for chapter entity files; see §17.2.3 Specifying DocBook output options.