diff --git a/lemon/error.h b/lemon/error.h
--- a/lemon/error.h
+++ b/lemon/error.h
@@ -41,11 +41,11 @@
   ///
   class Exception : public std::exception {
   public:
-    ///\e Constructor
-    Exception() {}
-    ///\e Virtual destructor
+    ///Constructor
+    Exception() throw() {}
+    ///Virtual destructor
     virtual ~Exception() throw() {}
-    ///\e A short description of the exception
+    ///A short description of the exception
     virtual const char* what() const throw() {
       return "lemon::Exception";
     }
@@ -64,29 +64,31 @@
   public:
 
     /// Copy constructor
-    IoError(const IoError &error) {
+    IoError(const IoError &error) throw() : Exception() {
       message(error._message);
       file(error._file);
     }
 
     /// Constructor
-    explicit IoError(const char *message) {
+    explicit IoError(const char *message) throw() {
       IoError::message(message);
     }
 
     /// Constructor
-    explicit IoError(const std::string &message) {
+    explicit IoError(const std::string &message) throw() {
       IoError::message(message);
     }
 
     /// Constructor
-    IoError(const std::string &file, const char *message) {
+    explicit IoError(const char *message,
+                     const std::string &file) throw() {
       IoError::message(message);
       IoError::file(file);
     }
 
     /// Constructor
-    IoError(const std::string &file, const std::string &message) {
+    explicit IoError(const std::string &message,
+                     const std::string &file) throw() {
       IoError::message(message);
       IoError::file(file);
     }
@@ -95,53 +97,50 @@
     virtual ~IoError() throw() {}
 
     /// Set the error message
-    void message(const char *message) {
+    void message(const char *message) throw() {
       try {
         _message = message;
       } catch (...) {}
     }
 
     /// Set the error message
-    void message(const std::string& message) {
+    void message(const std::string& message) throw() {
       try {
         _message = message;
       } catch (...) {}
     }
 
     /// Set the file name
-    void file(const std::string &file) {
+    void file(const std::string &file) throw() {
       try {
         _file = file;
       } catch (...) {}
     }
 
     /// Returns the error message
-    const std::string& message() const {
+    const std::string& message() const throw() {
       return _message;
     }
 
     /// \brief Returns the filename
     ///
-    /// Returns the filename or empty string if the filename was not
-    /// specified.
-    const std::string& file() const {
+    /// Returns the filename or an empty string if it was not specified.
+    const std::string& file() const throw() {
       return _file;
     }
 
     /// \brief Returns a short error message
     ///
-    /// Returns a short error message which contains the message, the
-    /// file name and the line number.
+    /// Returns a short error message which contains the message and the
+    /// file name.
     virtual const char* what() const throw() {
       try {
         _what.clear();
         std::ostringstream oss;
         oss << "lemon:IoError" << ": ";
-        oss << message();
-        if (!file().empty()) {
-          oss << " (";
-          if (!file().empty()) oss << "with file '" << file() << "'";
-          oss << ")";
+        oss << _message;
+        if (!_file.empty()) {
+          oss << " ('" << _file << "')";
         }
         _what = oss.str();
       }
@@ -154,8 +153,8 @@
 
   /// \brief Format error
   ///
-  /// This class is used to indicate if an input file has wrong
-  /// formatting, or a data representation is not legal.
+  /// This exception is thrown when an input file has wrong
+  /// format or a data representation is not legal.
   class FormatError : public Exception {
   protected:
     std::string _message;
@@ -166,33 +165,35 @@
   public:
 
     /// Copy constructor
-    FormatError(const FormatError &error) {
+    FormatError(const FormatError &error) throw() : Exception() {
       message(error._message);
       file(error._file);
       line(error._line);
     }
 
     /// Constructor
-    explicit FormatError(const char *message) {
+    explicit FormatError(const char *message) throw() {
       FormatError::message(message);
       _line = 0;
     }
 
     /// Constructor
-    explicit FormatError(const std::string &message) {
+    explicit FormatError(const std::string &message) throw() {
       FormatError::message(message);
       _line = 0;
     }
 
     /// Constructor
-    FormatError(const std::string &file, int line, const char *message) {
+    explicit FormatError(const char *message,
+                         const std::string &file, int line = 0) throw() {
       FormatError::message(message);
       FormatError::file(file);
       FormatError::line(line);
     }
 
     /// Constructor
-    FormatError(const std::string &file, int line, const std::string &message) {
+    explicit FormatError(const std::string &message,
+                         const std::string &file, int line = 0) throw() {
       FormatError::message(message);
       FormatError::file(file);
       FormatError::line(line);
@@ -202,24 +203,24 @@
     virtual ~FormatError() throw() {}
 
     /// Set the line number
-    void line(int line) { _line = line; }
+    void line(int line) throw() { _line = line; }
 
     /// Set the error message
-    void message(const char *message) {
+    void message(const char *message) throw() {
       try {
         _message = message;
       } catch (...) {}
     }
 
     /// Set the error message
-    void message(const std::string& message) {
+    void message(const std::string& message) throw() {
       try {
         _message = message;
       } catch (...) {}
     }
 
     /// Set the file name
-    void file(const std::string &file) {
+    void file(const std::string &file) throw() {
       try {
         _file = file;
       } catch (...) {}
@@ -228,18 +229,17 @@
     /// \brief Returns the line number
     ///
     /// Returns the line number or zero if it was not specified.
-    int line() const { return _line; }
+    int line() const throw() { return _line; }
 
     /// Returns the error message
-    const std::string& message() const {
+    const std::string& message() const throw() {
       return _message;
     }
 
     /// \brief Returns the filename
     ///
-    /// Returns the filename or empty string if the filename was not
-    /// specified.
-    const std::string& file() const {
+    /// Returns the filename or an empty string if it was not specified.
+    const std::string& file() const throw() {
       return _file;
     }
 
@@ -252,12 +252,12 @@
         _what.clear();
         std::ostringstream oss;
         oss << "lemon:FormatError" << ": ";
-        oss << message();
-        if (!file().empty() || line() != 0) {
+        oss << _message;
+        if (!_file.empty() || _line != 0) {
           oss << " (";
-          if (!file().empty()) oss << "in file '" << file() << "'";
-          if (!file().empty() && line() != 0) oss << " ";
-          if (line() != 0) oss << "at line " << line();
+          if (!_file.empty()) oss << "in file '" << _file << "'";
+          if (!_file.empty() && _line != 0) oss << " ";
+          if (_line != 0) oss << "at line " << _line;
           oss << ")";
         }
         _what = oss.str();
diff --git a/lemon/graph_to_eps.h b/lemon/graph_to_eps.h
--- a/lemon/graph_to_eps.h
+++ b/lemon/graph_to_eps.h
@@ -1170,7 +1170,7 @@
   std::ostream* os = new std::ofstream(file_name);
   if (!(*os)) {
     delete os;
-    throw IoError(file_name, "Cannot write file");
+    throw IoError("Cannot write file", file_name);
   }
   return GraphToEps<DefaultGraphToEpsTraits<G> >
     (DefaultGraphToEpsTraits<G>(g,*os,true));
@@ -1191,7 +1191,7 @@
   std::ostream* os = new std::ofstream(file_name.c_str());
   if (!(*os)) {
     delete os;
-    throw IoError(file_name, "Cannot write file");
+    throw IoError("Cannot write file", file_name);
   }
   return GraphToEps<DefaultGraphToEpsTraits<G> >
     (DefaultGraphToEpsTraits<G>(g,*os,true));
diff --git a/lemon/lgf_reader.h b/lemon/lgf_reader.h
--- a/lemon/lgf_reader.h
+++ b/lemon/lgf_reader.h
@@ -516,7 +516,7 @@
         _filename(fn), _digraph(digraph),
         _use_nodes(false), _use_arcs(false),
         _skip_nodes(false), _skip_arcs(false) {
-      if (!(*_is)) throw IoError(fn, "Cannot open file");
+      if (!(*_is)) throw IoError("Cannot open file", fn);
     }
 
     /// \brief Constructor
@@ -528,7 +528,7 @@
         _filename(fn), _digraph(digraph),
         _use_nodes(false), _use_arcs(false),
         _skip_nodes(false), _skip_arcs(false) {
-      if (!(*_is)) throw IoError(fn, "Cannot open file");
+      if (!(*_is)) throw IoError("Cannot open file", fn);
     }
 
     /// \brief Destructor
@@ -879,7 +879,7 @@
             maps.find(_node_maps[i].first);
           if (jt == maps.end()) {
             std::ostringstream msg;
-            msg << "Map not found in file: " << _node_maps[i].first;
+            msg << "Map not found: " << _node_maps[i].first;
             throw FormatError(msg.str());
           }
           map_index[i] = jt->second;
@@ -908,7 +908,7 @@
           }
         }
         if (line >> std::ws >> c)
-          throw FormatError("Extra character on the end of line");
+          throw FormatError("Extra character at the end of line");
 
         Node n;
         if (!_use_nodes) {
@@ -917,7 +917,7 @@
             _node_index.insert(std::make_pair(tokens[label_index], n));
         } else {
           if (label_index == -1)
-            throw FormatError("Label map not found in file");
+            throw FormatError("Label map not found");
           typename std::map<std::string, Node>::iterator it =
             _node_index.find(tokens[label_index]);
           if (it == _node_index.end()) {
@@ -972,7 +972,7 @@
             maps.find(_arc_maps[i].first);
           if (jt == maps.end()) {
             std::ostringstream msg;
-            msg << "Map not found in file: " << _arc_maps[i].first;
+            msg << "Map not found: " << _arc_maps[i].first;
             throw FormatError(msg.str());
           }
           map_index[i] = jt->second;
@@ -1010,7 +1010,7 @@
           }
         }
         if (line >> std::ws >> c)
-          throw FormatError("Extra character on the end of line");
+          throw FormatError("Extra character at the end of line");
 
         Arc a;
         if (!_use_arcs) {
@@ -1038,7 +1038,7 @@
             _arc_index.insert(std::make_pair(tokens[label_index], a));
         } else {
           if (label_index == -1)
-            throw FormatError("Label map not found in file");
+            throw FormatError("Label map not found");
           typename std::map<std::string, Arc>::iterator it =
             _arc_index.find(tokens[label_index]);
           if (it == _arc_index.end()) {
@@ -1073,13 +1073,13 @@
         if (!_reader_bits::readToken(line, token))
           throw FormatError("Attribute value not found");
         if (line >> c)
-          throw FormatError("Extra character on the end of line");
+          throw FormatError("Extra character at the end of line");
 
         {
           std::set<std::string>::iterator it = read_attr.find(attr);
           if (it != read_attr.end()) {
             std::ostringstream msg;
-            msg << "Multiple occurence of attribute " << attr;
+            msg << "Multiple occurence of attribute: " << attr;
             throw FormatError(msg.str());
           }
           read_attr.insert(attr);
@@ -1101,7 +1101,7 @@
            it != _attributes.end(); ++it) {
         if (read_attr.find(it->first) == read_attr.end()) {
           std::ostringstream msg;
-          msg << "Attribute not found in file: " << it->first;
+          msg << "Attribute not found: " << it->first;
           throw FormatError(msg.str());
         }
       }
@@ -1117,9 +1117,6 @@
     /// This function starts the batch processing
     void run() {
       LEMON_ASSERT(_is != 0, "This reader assigned to an other reader");
-      if (!*_is) {
-        throw FormatError("Cannot find file");
-      }
 
       bool nodes_done = _skip_nodes;
       bool arcs_done = _skip_arcs;
@@ -1138,7 +1135,7 @@
           _reader_bits::readToken(line, caption);
 
           if (line >> c)
-            throw FormatError("Extra character on the end of line");
+            throw FormatError("Extra character at the end of line");
 
           if (section == "nodes" && !nodes_done) {
             if (_nodes_caption.empty() || _nodes_caption == caption) {
@@ -1308,7 +1305,7 @@
         _filename(fn), _graph(graph),
         _use_nodes(false), _use_edges(false),
         _skip_nodes(false), _skip_edges(false) {
-      if (!(*_is)) throw IoError(fn, "Cannot open file");
+      if (!(*_is)) throw IoError("Cannot open file", fn);
     }
 
     /// \brief Constructor
@@ -1320,7 +1317,7 @@
         _filename(fn), _graph(graph),
         _use_nodes(false), _use_edges(false),
         _skip_nodes(false), _skip_edges(false) {
-      if (!(*_is)) throw IoError(fn, "Cannot open file");
+      if (!(*_is)) throw IoError("Cannot open file", fn);
     }
 
     /// \brief Destructor
@@ -1715,7 +1712,7 @@
             maps.find(_node_maps[i].first);
           if (jt == maps.end()) {
             std::ostringstream msg;
-            msg << "Map not found in file: " << _node_maps[i].first;
+            msg << "Map not found: " << _node_maps[i].first;
             throw FormatError(msg.str());
           }
           map_index[i] = jt->second;
@@ -1744,7 +1741,7 @@
           }
         }
         if (line >> std::ws >> c)
-          throw FormatError("Extra character on the end of line");
+          throw FormatError("Extra character at the end of line");
 
         Node n;
         if (!_use_nodes) {
@@ -1753,7 +1750,7 @@
             _node_index.insert(std::make_pair(tokens[label_index], n));
         } else {
           if (label_index == -1)
-            throw FormatError("Label map not found in file");
+            throw FormatError("Label map not found");
           typename std::map<std::string, Node>::iterator it =
             _node_index.find(tokens[label_index]);
           if (it == _node_index.end()) {
@@ -1808,7 +1805,7 @@
             maps.find(_edge_maps[i].first);
           if (jt == maps.end()) {
             std::ostringstream msg;
-            msg << "Map not found in file: " << _edge_maps[i].first;
+            msg << "Map not found: " << _edge_maps[i].first;
             throw FormatError(msg.str());
           }
           map_index[i] = jt->second;
@@ -1846,7 +1843,7 @@
           }
         }
         if (line >> std::ws >> c)
-          throw FormatError("Extra character on the end of line");
+          throw FormatError("Extra character at the end of line");
 
         Edge e;
         if (!_use_edges) {
@@ -1874,7 +1871,7 @@
             _edge_index.insert(std::make_pair(tokens[label_index], e));
         } else {
           if (label_index == -1)
-            throw FormatError("Label map not found in file");
+            throw FormatError("Label map not found");
           typename std::map<std::string, Edge>::iterator it =
             _edge_index.find(tokens[label_index]);
           if (it == _edge_index.end()) {
@@ -1909,13 +1906,13 @@
         if (!_reader_bits::readToken(line, token))
           throw FormatError("Attribute value not found");
         if (line >> c)
-          throw FormatError("Extra character on the end of line");
+          throw FormatError("Extra character at the end of line");
 
         {
           std::set<std::string>::iterator it = read_attr.find(attr);
           if (it != read_attr.end()) {
             std::ostringstream msg;
-            msg << "Multiple occurence of attribute " << attr;
+            msg << "Multiple occurence of attribute: " << attr;
             throw FormatError(msg.str());
           }
           read_attr.insert(attr);
@@ -1937,7 +1934,7 @@
            it != _attributes.end(); ++it) {
         if (read_attr.find(it->first) == read_attr.end()) {
           std::ostringstream msg;
-          msg << "Attribute not found in file: " << it->first;
+          msg << "Attribute not found: " << it->first;
           throw FormatError(msg.str());
         }
       }
@@ -1972,7 +1969,7 @@
           _reader_bits::readToken(line, caption);
 
           if (line >> c)
-            throw FormatError("Extra character on the end of line");
+            throw FormatError("Extra character at the end of line");
 
           if (section == "nodes" && !nodes_done) {
             if (_nodes_caption.empty() || _nodes_caption == caption) {
@@ -2095,7 +2092,7 @@
     SectionReader(const std::string& fn)
       : _is(new std::ifstream(fn.c_str())), local_is(true),
         _filename(fn) {
-      if (!(*_is)) throw IoError(fn, "Cannot open file");
+      if (!(*_is)) throw IoError("Cannot open file", fn);
     }
 
     /// \brief Constructor
@@ -2104,7 +2101,7 @@
     SectionReader(const char* fn)
       : _is(new std::ifstream(fn)), local_is(true),
         _filename(fn) {
-      if (!(*_is)) throw IoError(fn, "Cannot open file");
+      if (!(*_is)) throw IoError("Cannot open file", fn);
     }
 
     /// \brief Destructor
@@ -2261,11 +2258,11 @@
           _reader_bits::readToken(line, caption);
 
           if (line >> c)
-            throw FormatError("Extra character on the end of line");
+            throw FormatError("Extra character at the end of line");
 
           if (extra_sections.find(section) != extra_sections.end()) {
             std::ostringstream msg;
-            msg << "Multiple occurence of section " << section;
+            msg << "Multiple occurence of section: " << section;
             throw FormatError(msg.str());
           }
           Sections::iterator it = _sections.find(section);
@@ -2387,7 +2384,7 @@
     /// file.
     LgfContents(const std::string& fn)
       : _is(new std::ifstream(fn.c_str())), local_is(true) {
-      if (!(*_is)) throw IoError(fn, "Cannot open file");
+      if (!(*_is)) throw IoError("Cannot open file", fn);
     }
 
     /// \brief Constructor
@@ -2396,7 +2393,7 @@
     /// file.
     LgfContents(const char* fn)
       : _is(new std::ifstream(fn)), local_is(true) {
-      if (!(*_is)) throw IoError(fn, "Cannot open file");
+      if (!(*_is)) throw IoError("Cannot open file", fn);
     }
 
     /// \brief Destructor
diff --git a/lemon/lgf_writer.h b/lemon/lgf_writer.h
--- a/lemon/lgf_writer.h
+++ b/lemon/lgf_writer.h
@@ -463,7 +463,7 @@
     DigraphWriter(const std::string& fn, const Digraph& digraph)
       : _os(new std::ofstream(fn.c_str())), local_os(true), _digraph(digraph),
         _skip_nodes(false), _skip_arcs(false) {
-      if (!(*_os)) throw IoError(fn, "Cannot write file");
+      if (!(*_os)) throw IoError("Cannot write file", fn);
     }
 
     /// \brief Constructor
@@ -473,7 +473,7 @@
     DigraphWriter(const char* fn, const Digraph& digraph)
       : _os(new std::ofstream(fn)), local_os(true), _digraph(digraph),
         _skip_nodes(false), _skip_arcs(false) {
-      if (!(*_os)) throw IoError(fn, "Cannot write file");
+      if (!(*_os)) throw IoError("Cannot write file", fn);
     }
 
     /// \brief Destructor
@@ -1023,7 +1023,7 @@
     GraphWriter(const std::string& fn, const Graph& graph)
       : _os(new std::ofstream(fn.c_str())), local_os(true), _graph(graph),
         _skip_nodes(false), _skip_edges(false) {
-      if (!(*_os)) throw IoError(fn, "Cannot write file");
+      if (!(*_os)) throw IoError("Cannot write file", fn);
     }
 
     /// \brief Constructor
@@ -1033,7 +1033,7 @@
     GraphWriter(const char* fn, const Graph& graph)
       : _os(new std::ofstream(fn)), local_os(true), _graph(graph),
         _skip_nodes(false), _skip_edges(false) {
-      if (!(*_os)) throw IoError(fn, "Cannot write file");
+      if (!(*_os)) throw IoError("Cannot write file", fn);
     }
 
     /// \brief Destructor
@@ -1585,7 +1585,7 @@
     /// Construct a section writer, which writes into the given file.
     SectionWriter(const std::string& fn)
       : _os(new std::ofstream(fn.c_str())), local_os(true) {
-      if (!(*_os)) throw IoError(fn, "Cannot write file");
+      if (!(*_os)) throw IoError("Cannot write file", fn);
     }
 
     /// \brief Constructor
@@ -1593,7 +1593,7 @@
     /// Construct a section writer, which writes into the given file.
     SectionWriter(const char* fn)
       : _os(new std::ofstream(fn)), local_os(true) {
-      if (!(*_os)) throw IoError(fn, "Cannot write file");
+      if (!(*_os)) throw IoError("Cannot write file", fn);
     }
 
     /// \brief Destructor