anchor.diff:  print1_tail(S, D) -> [" . "|print1(S, D)].
   
   %% quote_symbol(Symbol, SymbChars) -> bool().
  -%% Check if symbol needs to be quoted when printed. If it can read as
  -%% a number then it must be quoted.
  -
  -quote_symbol('.', _) -> true;            %Needs quoting
  +%%  Check if symbol needs to be quoted when printed. If it can read as
  +%%  a number then it must be quoted.
  +
  +quote_symbol('.', _) -> true;                   %Needs quoting
   quote_symbol(_, [C|Cs]=Cs0) ->
       case catch {ok,list_to_float(Cs0)} of
       {ok,_} -> true;
  
positive.code: 
  start_symb_char($#) -> false;
  start_symb_char($`) -> false;
  start_symb_char($') -> false;            %'
  start_symb_char($,) -> false;
  start_symb_char($|) -> false;            %Symbol quote character
  start_symb_char(C) -> symb_char(C).
  
  symb_char($() -> false;
  
negative.code: print1_string1([C|Cs], Q) ->
      string_char(C, Q, print1_string1(Cs, Q)).
  
  string_char(Q, Q, Tail) -> [$\\,Q|Tail];        %Must check these first!
  string_char($\\, _, Tail) -> [$\\,$\\|Tail];
  string_char(C, _, Tail) when C >= $\s, C =< $~ ->
      [C|Tail];
  string_char(C, _, Tail) when C >= $\240, C =< $\377 ->
      [C|Tail];
  string_char($\n, _, Tail) -> [$\\,$n|Tail];     %\n = LF
  string_char($\r, _, Tail) -> [$\\,$r|Tail];     %\r = CR
  string_char($\t, _, Tail) -> [$\\,$t|Tail];     %\t = TAB
  string_char($\v, _, Tail) -> [$\\,$v|Tail];     %\v = VT
  string_char($\b, _, Tail) -> [$\\,$b|Tail];     %\b = BS
  string_char($\f, _, Tail) -> [$\\,$f|Tail];     %\f = FF
  string_char($\e, _, Tail) -> [$\\,$e|Tail];     %\e = ESC
  string_char($\d, _, Tail) -> [$\\,$d|Tail];     %\d = DEL
  string_char(C, _, Tail) ->
      %%Unicode and other control characters.
      "\\x" ++ erlang:integer_to_list(C, 16) ++ ";" ++ Tail.
  
  %% prettyprint([IoDevice], Sexpr) -> ok.
  %% prettyprint1(Sexpr, Depth, Indentation, LineLength) -> [char()].
  