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:                              end, sort(St#leex.warnings))
               end, report_warnings, St#leex.opts).
  
  add_error(E, St) ->
      add_error(St#leex.xfile, E, St).
  
  
negative.code:                  "unterminated " ++ Cs;
               {illegal_char,Cs} ->
                   "illegal character " ++ Cs;
  %%           {posix_cc,What} ->
  %%               ["illegal POSIX character class ",io_lib:write_string(What)];
               {char_class,What} ->
                   ["illegal character class ",io_lib:write_string(What)]
           end,
  