namespace boost {
  namespace text {
    struct collation_compare;
    struct collation_table;
    bool operator==(collation_table const & lhs, collation_table const & rhs);
    bool operator!=(collation_table const & lhs, collation_table const & rhs);
    collation_table default_collation_table();
    collation_table 
    tailored_collation_table(string_view, string_view = "", 
                             parser_diagnostic_callback = parser_diagnostic_callback(), 
                             parser_diagnostic_callback = parser_diagnostic_callback());
  }
}