anchor.diff:  %% posix_cc(String) -> {PosixClass,RestString}.
   %%  Handle POSIX character classes.
   
  -posix_cc("alnum" ++ Cs) -> {alnum,Cs};
  -posix_cc("alpha" ++ Cs) -> {alpha,Cs};
  -posix_cc("blank" ++ Cs) -> {blank,Cs};
  -posix_cc("cntrl" ++ Cs) -> {cntrl,Cs};
  -posix_cc("digit" ++ Cs) -> {digit,Cs};
  -posix_cc("graph" ++ Cs) -> {graph,Cs};
  -posix_cc("lower" ++ Cs) -> {lower,Cs};
  -posix_cc("print" ++ Cs) -> {print,Cs};
  -posix_cc("punct" ++ Cs) -> {punct,Cs};
  -posix_cc("space" ++ Cs) -> {space,Cs};
  -posix_cc("upper" ++ Cs) -> {upper,Cs};
  -posix_cc("xdigit" ++ Cs) -> {xdigit,Cs};
  -posix_cc(Cs) -> parse_error({posix_cc,substr(Cs, 1, 5)}).
  +%% posix_cc("alnum" ++ Cs) -> {alnum,Cs};
  +%% posix_cc("alpha" ++ Cs) -> {alpha,Cs};
  +%% posix_cc("blank" ++ Cs) -> {blank,Cs};
  +%% posix_cc("cntrl" ++ Cs) -> {cntrl,Cs};
  +%% posix_cc("digit" ++ Cs) -> {digit,Cs};
  +%% posix_cc("graph" ++ Cs) -> {graph,Cs};
  +%% posix_cc("lower" ++ Cs) -> {lower,Cs};
  +%% posix_cc("print" ++ Cs) -> {print,Cs};
  +%% posix_cc("punct" ++ Cs) -> {punct,Cs};
  +%% posix_cc("space" ++ Cs) -> {space,Cs};
  +%% posix_cc("upper" ++ Cs) -> {upper,Cs};
  +%% posix_cc("xdigit" ++ Cs) -> {xdigit,Cs};
  +%% posix_cc(Cs) -> parse_error({posix_cc,substr(Cs, 1, 5)}).
   
   escape_char($n) -> $\n;                         % \n = LF
   escape_char($r) -> $\r;                         % \r = CR
  
positive.code: special_char($*, _) -> true;
  special_char($+, _) -> true;
  special_char($?, _) -> true;
  special_char(${, #leex{posix=true}) -> true;    % Only when POSIX set
  special_char($\\, _) -> true;
  special_char(_, _) -> false.
  
  
negative.code:     re_char_class(Cs, [$]], St);
  re_char_class(Cs, St) -> re_char_class(Cs, [], St).
  
  %% re_char_class("[:" ++ Cs0, Cc, #leex{posix=true}=St) ->
  %%     %% POSIX char class only.
  %%     case posix_cc(Cs0) of
  %%         {Pcl,":]" ++ Cs1} -> re_char_class(Cs1, [{posix,Pcl}|Cc], St);
  %%         {_,Cs1} -> parse_error({posix_cc,string_between(Cs0, Cs1)})
  %%     end;
  re_char_class([C1|Cs0], Cc, St) when C1 =/= $] ->
      case re_char(C1, Cs0) of
          {Cf,[$-,C2|Cs1]} when C2 =/= $] ->
  