///
int docbook(odocstream &, OutputParams const &) const;
///
docstring xhtml(XHTMLStream &, OutputParams const &) const;
///
void validate(LaTeXFeatures &) const {}
///
int docbook(odocstream &, OutputParams const &) const;
///
docstring xhtml(XHTMLStream &, OutputParams const &) const;
///
void validate(LaTeXFeatures &) const {}