# File lib/mail/parsers/rfc2822.rb, line 4480
    def _nt_id_right
      start_index = index
      if node_cache[:id_right].has_key?(index)
        cached = node_cache[:id_right][index]
        @index = cached.interval.end if cached
        return cached
      end

      i0 = index
      r1 = _nt_msg_id_dot_atom_text
      if r1
        r0 = r1
      else
        r2 = _nt_no_fold_literal
        if r2
          r0 = r2
        else
          r3 = _nt_obs_id_right
          if r3
            r0 = r3
          else
            @index = i0
            r0 = nil
          end
        end
      end

      node_cache[:id_right][start_index] = r0

      r0
    end