///
int plaintext(odocstringstream & ods, OutputParams const & op,
size_t max_length = INT_MAX) const;
///
int docbook(odocstream &, OutputParams const &) const;
///
int plaintext(odocstringstream & ods, OutputParams const & op,
size_t max_length = INT_MAX) const;
///
int docbook(odocstream &, OutputParams const &) const;