diff --git a/demo/arg_parser_demo.cc b/demo/arg_parser_demo.cc
--- a/demo/arg_parser_demo.cc
+++ b/demo/arg_parser_demo.cc
@@ -29,43 +29,62 @@
 using namespace lemon;
 int main(int argc, const char **argv)
 {
-  ArgParser ap(argc,argv);
+  // Initialize the argument parser
+  ArgParser ap(argc, argv);
   int i;
   std::string s;
-  double d;
-  bool b,sil;
-  bool g1,g2,g3;
-  ap.refOption("n", "An integer input.", i, true)
-    .refOption("val", "A double input.", d)
-    .doubleOption("val2", "A double input.", d)
-    .synonym("vals","val")
-    .refOption("name", "A string input.", s)
-    .refOption("f", "A switch.", b)
-    .refOption("nohelp", "", sil)
-    .refOption("gra","Choice A",g1)
-    .refOption("grb","Choice B",g2)
-    .refOption("grc","Choice C",g3)
-    .optionGroup("gr","gra")
-    .optionGroup("gr","grb")
-    .optionGroup("gr","grc")
-    .mandatoryGroup("gr")
-    .onlyOneGroup("gr")
-    .other("infile","The input file.")
+  double d = 1.0;
+  bool b, nh;
+  bool g1, g2, g3;
+
+  // Add a mandatory integer option with storage reference
+  ap.refOption("n", "An integer input.", i, true);
+  // Add a double option with storage reference (the default value is 1.0)
+  ap.refOption("val", "A double input.", d);
+  // Add a double option without storage reference (the default value is 3.14)
+  ap.doubleOption("val2", "A double input.", 3.14);
+  // Set synonym for -val option
+  ap.synonym("vals", "val");
+  // Add a string option
+  ap.refOption("name", "A string input.", s);
+  // Add bool options
+  ap.refOption("f", "A switch.", b)
+    .refOption("nohelp", "", nh)
+    .refOption("gra", "Choice A", g1)
+    .refOption("grb", "Choice B", g2)
+    .refOption("grc", "Choice C", g3);
+  // Bundle -gr* options into a group
+  ap.optionGroup("gr", "gra")
+    .optionGroup("gr", "grb")
+    .optionGroup("gr", "grc");
+  // Set the group mandatory
+  ap.mandatoryGroup("gr");
+  // Set the options of the group exclusive (only one option can be given)
+  ap.onlyOneGroup("gr");
+  // Add non-parsed arguments (e.g. input files)
+  ap.other("infile", "The input file.")
     .other("...");
   
+  // Perform the parsing process
+  // (in case of any error it terminates the program)
   ap.parse();
 
+  // Check each option if it has been given and print its value
   std::cout << "Parameters of '" << ap.commandName() << "':\n";
 
-  if(ap.given("n")) std::cout << "  Value of -n: " << i << std::endl;
+  std::cout << "  Value of -n: " << i << std::endl;
   if(ap.given("val")) std::cout << "  Value of -val: " << d << std::endl;
+  if(ap.given("val2")) {
+    d = ap["val2"];
+    std::cout << "  Value of -val2: " << d << std::endl;
+  }
   if(ap.given("name")) std::cout << "  Value of -name: " << s << std::endl;
   if(ap.given("f")) std::cout << "  -f is given\n";
-  if(ap.given("nohelp")) std::cout << "  Value of -nohelp: " << sil << std::endl;
+  if(ap.given("nohelp")) std::cout << "  Value of -nohelp: " << nh << std::endl;
   if(ap.given("gra")) std::cout << "  -gra is given\n";
   if(ap.given("grb")) std::cout << "  -grb is given\n";
   if(ap.given("grc")) std::cout << "  -grc is given\n";
-                                     
+  
   switch(ap.files().size()) {
   case 0:
     std::cout << "  No file argument was given.\n";
@@ -80,4 +99,5 @@
   for(unsigned int i=0;i<ap.files().size();++i)
     std::cout << "    '" << ap.files()[i] << "'\n";
   
+  return 0;
 }
diff --git a/lemon/arg_parser.h b/lemon/arg_parser.h
--- a/lemon/arg_parser.h
+++ b/lemon/arg_parser.h
@@ -118,13 +118,19 @@
     
   public:
 
-    ///\e
+    ///Constructor
     ArgParser(int argc, const char **argv);
 
     ~ArgParser();
 
+    ///\name Options
+    ///
+
+    ///@{
+
     ///Add a new integer type option
 
+    ///Add a new integer type option.
     ///\param name The name of the option. The leading '-' must be omitted.
     ///\param help A help string.
     ///\param value A default value for the option.
@@ -135,6 +141,7 @@
 
     ///Add a new floating point type option
 
+    ///Add a new floating point type option.
     ///\param name The name of the option. The leading '-' must be omitted.
     ///\param help A help string.
     ///\param value A default value for the option.
@@ -145,6 +152,7 @@
 
     ///Add a new bool type option
 
+    ///Add a new bool type option.
     ///\param name The name of the option. The leading '-' must be omitted.
     ///\param help A help string.
     ///\param value A default value for the option.
@@ -156,6 +164,7 @@
 
     ///Add a new string type option
 
+    ///Add a new string type option.
     ///\param name The name of the option. The leading '-' must be omitted.
     ///\param help A help string.
     ///\param value A default value for the option.
@@ -164,7 +173,17 @@
 		      const std::string &help,
 		      std::string value="", bool obl=false);
 
-    ///\name Options with external storage
+    ///Give help string for non-parsed arguments.
+
+    ///With this function you can give help string for non-parsed arguments.
+    ///The parameter \c name will be printed in the short usage line, while
+    ///\c help gives a more detailed description.
+    ArgParser &other(const std::string &name,
+		     const std::string &help="");
+    
+    ///@}
+
+    ///\name Options with External Storage
     ///Using this functions, the value of the option will be directly written
     ///into a variable once the option appears in the command line.
 
@@ -172,6 +191,7 @@
 
     ///Add a new integer type option with a storage reference
 
+    ///Add a new integer type option with a storage reference.
     ///\param name The name of the option. The leading '-' must be omitted.
     ///\param help A help string.
     ///\param obl Indicate if the option is mandatory.
@@ -182,6 +202,7 @@
 
     ///Add a new floating type option with a storage reference
 
+    ///Add a new floating type option with a storage reference.
     ///\param name The name of the option. The leading '-' must be omitted.
     ///\param help A help string.
     ///\param obl Indicate if the option is mandatory.
@@ -192,6 +213,7 @@
 
     ///Add a new bool type option with a storage reference
 
+    ///Add a new bool type option with a storage reference.
     ///\param name The name of the option. The leading '-' must be omitted.
     ///\param help A help string.
     ///\param obl Indicate if the option is mandatory.
@@ -203,6 +225,7 @@
 
     ///Add a new string type option with a storage reference
 
+    ///Add a new string type option with a storage reference.
     ///\param name The name of the option. The leading '-' must be omitted.
     ///\param help A help string.
     ///\param obl Indicate if the option is mandatory.
@@ -218,7 +241,7 @@
     
     ///@{
 
-    ///Boundle some options into a group
+    ///Bundle some options into a group
 
     /// You can group some option by calling this function repeatedly for each
     /// option to be grouped with the same groupname.
@@ -230,7 +253,7 @@
     ///Make the members of a group exclusive
 
     ///If you call this function for a group, than at most one of them can be
-    ///given at the same time
+    ///given at the same time.
     ArgParser &onlyOneGroup(const std::string &group);
   
     ///Make a group mandatory
@@ -248,23 +271,6 @@
     
     ///@}
 
-    ///Give help string for non-parsed arguments.
-
-    ///With this function you can give help string for non-parsed arguments.
-    ///The parameter \c name will be printed in the short usage line, while
-    ///\c help gives a more detailed description.
-    ArgParser &other(const std::string &name,
-		     const std::string &help="");
-    
-    ///Give back the non-option type arguments.
-
-    ///Give back a reference to a vector consisting of the program arguments
-    ///not starting with a '-' character.
-    std::vector<std::string> &files() { return _file_args; }
-
-    ///Give back the command name (the 0th argument)
-    const std::string &commandName() { return _command_name; }
-
     void show(std::ostream &os,Opts::iterator i);
     void show(std::ostream &os,Groups::iterator i);
     void showHelp(Opts::iterator i);
@@ -286,6 +292,9 @@
       return parse();
     }
     
+    ///Give back the command name (the 0th argument)
+    const std::string &commandName() { return _command_name; }
+
     ///Check if an opion has been given to the command.
     bool given(std::string op) 
     {
@@ -360,10 +369,14 @@
     {
       return RefType(*this, n);
     }    
+
+    ///Give back the non-option type arguments.
+
+    ///Give back a reference to a vector consisting of the program arguments
+    ///not starting with a '-' character.
+    std::vector<std::string> &files() { return _file_args; }
  
   };
 }
 
-    
-
-#endif // LEMON_MAIN_PARAMS
+#endif // LEMON_ARG_PARSER