anchor.diff:  
   
   re() ->
  -    "^(
  +    "(
               (\"[^\"\\f\\n\\r\\t\\v\\b]+\")
           |   ([\\w\\!\\#\\$\\%\\&\'\\*\\+\\-\\~\\/\\^\\`\\|\\{\\}]+
                   (\\.[\\w\\!\\#\\$\\%\\&\\'\\*\\+\\-\\~\\/\^\`\\|\\{\\}]+)*
  
positive.code:             ([A-Za-z0-9\\-])+\\.
          )+
          [A-Za-z\\-]{2,}
      )$".
  
  %% Rusty's regexp: "([^@\"\'\\s]+)@(([-a-z0-9]+\\.)+[a-z]{2,})".
  %% Complete regexp:
  
negative.code:     case z_string:trim(Value) of
          [] -> {{ok, []}, Context};
          Trimmed ->
              case re:run(Trimmed, [$^|re()]++"$", [extended]) of
                  nomatch   -> {{error, Id, invalid}, Context};
                  {match,_} -> {{ok, Trimmed}, Context}
              end
  