# File lib/mail/parsers/rfc2822_obsolete.rb, line 679
    def _nt_obs_day
      start_index = index
      if node_cache[:obs_day].has_key?(index)
        cached = node_cache[:obs_day][index]
        if cached
          cached = SyntaxNode.new(input, index...(index + 1)) if cached == true
          @index = cached.interval.end
        end
        return cached
      end

      i0, s0 = index, []
      r2 = _nt_CFWS
      if r2
        r1 = r2
      else
        r1 = instantiate_node(SyntaxNode,input, index...index)
      end
      s0 << r1
      if r1
        i3 = index
        r4 = _nt_DIGIT
        if r4
          r3 = r4
        else
          i5, s5 = index, []
          r6 = _nt_DIGIT
          s5 << r6
          if r6
            r7 = _nt_DIGIT
            s5 << r7
          end
          if s5.last
            r5 = instantiate_node(SyntaxNode,input, i5...index, s5)
            r5.extend(ObsDay0)
          else
            @index = i5
            r5 = nil
          end
          if r5
            r3 = r5
          else
            @index = i3
            r3 = nil
          end
        end
        s0 << r3
        if r3
          r9 = _nt_CFWS
          if r9
            r8 = r9
          else
            r8 = instantiate_node(SyntaxNode,input, index...index)
          end
          s0 << r8
        end
      end
      if s0.last
        r0 = instantiate_node(SyntaxNode,input, i0...index, s0)
        r0.extend(ObsDay1)
      else
        @index = i0
        r0 = nil
      end

      node_cache[:obs_day][start_index] = r0

      r0
    end