diff --git a/src/utility/settings.cpp b/src/utility/settings.cpp
index e216134b1..c5b84db95 100644
--- a/src/utility/settings.cpp
+++ b/src/utility/settings.cpp
@@ -7,6 +7,10 @@
 
 #include "src/utility/settings.h"
 
+#include "log4cplus/logger.h"
+#include "log4cplus/loggingmacros.h"
+extern log4cplus::Logger logger;
+
 namespace mrmc {
 namespace settings {
 
@@ -17,6 +21,7 @@ namespace bpo = boost::program_options;
  */
 bpo::options_description* mrmc::settings::Settings::cli = nullptr;
 bpo::options_description* mrmc::settings::Settings::conf = nullptr;
+std::string mrmc::settings::Settings::binaryName = "";
 mrmc::settings::Settings* mrmc::settings::Settings::inst = nullptr;
 
 /*!
@@ -35,6 +40,7 @@ mrmc::settings::Settings* mrmc::settings::Settings::inst = nullptr;
 Settings::Settings(const int argc, const char* argv[], const char* filename)
 	: configfile("Config Options"), generic("Generic Options"), commandline("Commandline Options")
 {
+	Settings::binaryName = std::string(argv[0]);
 	try
 	{
 		//! Initially fill description objects and call register callbacks
@@ -73,29 +79,35 @@ Settings::Settings(const int argc, const char* argv[], const char* filename)
 		
 		//! Finalize parsed options, check for specified requirements
 		bpo::notify(this->vm);
+		LOG4CPLUS_DEBUG(logger, "Finished loading config.");
 	}
 	catch (bpo::reading_file e)
 	{
 		std::cerr << "Could not read config file " << filename << std::endl;
+		LOG4CPLUS_ERROR(logger, "Could not read config file");
 	}
 	catch (bpo::required_option e)
 	{
-		std::cerr << "required option: " << e.what() << std::endl;
+		std::cerr << "Required option: " << e.what() << std::endl;
+		LOG4CPLUS_ERROR(logger, "Required option: " << e.what());
 		throw mrmc::exceptions::InvalidSettings();
 	}
 	catch (bpo::validation_error e)
 	{
 		std::cerr << "Validation failed: " << e.what() << std::endl;
+		LOG4CPLUS_ERROR(logger, "Validation failed: " << e.what());
 		throw mrmc::exceptions::InvalidSettings();
 	}
 	catch (bpo::invalid_command_line_syntax e)
 	{
 		std::cerr << "Invalid command line syntax: " << e.what() << std::endl;
+		LOG4CPLUS_ERROR(logger, "Invalid command line syntax: " << e.what());
 		throw mrmc::exceptions::InvalidSettings();
 	}
 	catch (bpo::error e)
 	{
 		std::cerr << e.what() << std::endl;
+		LOG4CPLUS_ERROR(logger, "Unknown error: " << e.what());
 		throw mrmc::exceptions::InvalidSettings();
 	}
 }
@@ -106,6 +118,7 @@ Settings::Settings(const int argc, const char* argv[], const char* filename)
  */
 void Settings::initDescriptions()
 {
+	LOG4CPLUS_DEBUG(logger, "Initializing descriptions.");
 	this->commandline.add_options()
 		("help,h", "produce help message")
 		("verbose,v", "be verbose")
@@ -154,6 +167,7 @@ void Settings::initDescriptions()
  */
 void Settings::firstRun(const int argc, const char* argv[], const char* filename)
 {
+	LOG4CPLUS_DEBUG(logger, "Performing first run.");
 	//! parse command line
 	bpo::store(bpo::command_line_parser(argc, argv).options(*(Settings::cli)).allow_unregistered().run(), this->vm);
 
@@ -197,7 +211,7 @@ void Settings::firstRun(const int argc, const char* argv[], const char* filename
 		catch (boost::bad_any_cast e)
 		{
 			std::cerr << "An intermediate callback failed." << std::endl;
-			std::cerr << e.what() << std::endl;
+			LOG4CPLUS_ERROR(logger, "An intermediate callback failed.\n" << e.what());
 		}
 	}
 }
@@ -211,6 +225,7 @@ void Settings::firstRun(const int argc, const char* argv[], const char* filename
  */
 void Settings::secondRun(const int argc, const char* argv[], const char* filename)
 {
+	LOG4CPLUS_DEBUG(logger, "Performing second run.");
 	//! Parse command line
 	bpo::store(bpo::command_line_parser(argc, argv).options(*(Settings::cli)).positional(this->positional).run(), this->vm);
 	/*
@@ -238,6 +253,7 @@ void Settings::secondRun(const int argc, const char* argv[], const char* filenam
 		if (! (*fptr)(this->vm))
 		{
 			std::cerr << "Custom option checker failed." << std::endl;
+			LOG4CPLUS_ERROR(logger, "A checker callback returned false.");
 			throw mrmc::exceptions::InvalidSettings();
 		}
 	}
@@ -253,8 +269,8 @@ void Settings::secondRun(const int argc, const char* argv[], const char* filenam
  */
 std::ostream& help(std::ostream& os)
 {
-	os << "Usage: <binary> [options] <transition file> <label file>" << std::endl;
-	os << *(mrmc::settings::Settings::cli) << std::endl;;
+	os << "Usage: " << mrmc::settings::Settings::binaryName << " [options] <transition file> <label file>" << std::endl;
+	os << *(mrmc::settings::Settings::cli) << std::endl;
 	return os;
 }
 
diff --git a/src/utility/settings.h b/src/utility/settings.h
index 56aaed33b..993fdc241 100644
--- a/src/utility/settings.h
+++ b/src/utility/settings.h
@@ -24,6 +24,12 @@ namespace mrmc {
 namespace settings {
 	
 	namespace bpo = boost::program_options;
+	/*
+	 *	Sorry for very long comment at this point (for the class), but all
+	 *	methods are private, hence there is no other place to explain the
+	 *	inner workings of this class that are necessary to understand the
+	 *	callback concept...
+	 */
 	/*!
 	 *	@brief	Simple wrapper around boost::program_options to handle configuration options.
 	 *
@@ -31,43 +37,68 @@ namespace settings {
 	 *	commandline and additionally load options from a file.
 	 *
 	 *	It is meant to be used as a singleton. Call 
-	 *	@code mrmc::settings::Settings::instance(argc, argv, filename) @endcode
+	 *	@code mrmc::settings::newInstance(argc, argv, filename) @endcode
 	 *	to initialize it and obtain an instance for the first time.
-	 *	Afterwards, it is possible to use
+	 *	Afterwards, use
 	 *	@code mrmc::settings::instance() @endcode
+	 *
+	 *	This class can be customized by other parts of the software using
+	 *	callbacks. There are three types of callbacks: register,
+	 *	intermediate and checker.
+	 *
+	 *	The (private) constructor will start with filling the internal
+	 *	options_description object. There are a few generic options like
+	 *	--help or --verbose. Then if calls all register callbacks that may
+	 *	add more options.
+	 *
+	 *	Then, it will start with a sloppy parsing run, allowing unregistered 
+	 *	options and ignoring further constraints from the options_description 
+	 *	objects.
+	 *
+	 *	After that, it will call all intermediate callbacks. They can
+	 *	inspect the options from the first run and add more options, e.g.
+	 *	enable more options for a specific component that has been enabled.
+	 *
+	 *	Using the new options_description objects, the constructor performs
+	 *	a second run. This time, it will not allow unregistered options and
+	 *	will check for required and positional arguments.
+	 *
+	 *	Finally, all checker callbacks will be called. They can check the
+	 *	final options for more complex requirements. If any of those checker
+	 *	callbacks returns false, a InvalidSettings exception will be thrown.
 	 */
 	class Settings
 	{
 		public:
 		
-		/*!
-		 *	@brief Get value of a generic option.
-		 */
-		template <typename T>
-		const T& get(const std::string &name) const {
-			std::cerr << "get(" << name << ")" << std::endl;
-			if (this->vm.count(name) == 0) throw mrmc::exceptions::InvalidSettings();
-			return this->vm[name].as<T>();
-		}
+			/*!
+			 *	@brief Get value of a generic option.
+			 */
+			template <typename T>
+			const T& get(const std::string &name) const {
+				std::cerr << "get(" << name << ")" << std::endl;
+				if (this->vm.count(name) == 0) throw mrmc::exceptions::InvalidSettings();
+				return this->vm[name].as<T>();
+			}
 		
-		/*!
-		 *	@brief Get value of string option
-		 */
-		const std::string& getString(const std::string &name) const {
-			return this->get<std::string>(name);
-		}
+			/*!
+			 *	@brief Get value of string option
+			 */
+			const std::string& getString(const std::string &name) const {
+				return this->get<std::string>(name);
+			}
 		
-		/*!
-		 *	@brief Check if an option is set
-		 */
-		const bool isSet(const std::string &name) const {
-			return this->vm.count(name) > 0;
-		}
+			/*!
+			 *	@brief Check if an option is set
+			 */
+			const bool isSet(const std::string &name) const {
+				return this->vm.count(name) > 0;
+			}
 	
-		friend std::ostream& help(std::ostream& os);
-		friend std::ostream& helpConfigfile(std::ostream& os);
-		friend Settings* instance();
-		friend Settings* newInstance(const int argc, const char* argv[], const char* filename);
+			friend std::ostream& help(std::ostream& os);
+			friend std::ostream& helpConfigfile(std::ostream& os);
+			friend Settings* instance();
+			friend Settings* newInstance(const int argc, const char* argv[], const char* filename);
 
 		private:
 			/*!
@@ -121,6 +152,11 @@ namespace settings {
 			 */
 			bpo::variables_map vm;
 			
+			/*!
+			 *	@brief name of binary
+			 */
+			static std::string binaryName;
+			
 			/*!
 			 *	@brief	actual instance of this class.
 			 */