diff --git a/src/xml-cxx/xml.hxx b/src/xml-cxx/xml.hxx
index c1fdb44..8554ae1 100644
--- a/src/xml-cxx/xml.hxx
+++ b/src/xml-cxx/xml.hxx
@@ -5,8 +5,8 @@
 //       1         2         3         4         5         6         7         8
 // 45678901234567890123456789012345678901234567890123456789012345678901234567890
 
-#ifndef XML_HXX
-#define XML_HXX
+#ifndef LIB_XML_CXX_HXX
+#define LIB_XML_CXX_HXX
 
 #include <istream>
 #include <string>
@@ -85,9 +85,10 @@ namespace xml {
   //----------------------------------------------------------------------------
   class type_mismatch: public exception {
     public:
-      type_mismatch(const Node& t, const std::string& txt) throw():
-          exception("wrong type, text contains mismatching character\ntext: "
-                    +txt, t) {}
+      type_mismatch(const Node& t, const std::string& txt,
+                    const std::string& comment) throw():
+          exception("wrong type, text contains mismatching character\n"+comment
+                    +"\ntext: "+txt, t) {}
   };
   //----------------------------------------------------------------------------
   class access_error: public exception {
@@ -266,25 +267,20 @@ namespace xml {
           throw();
       virtual String& append(const Node& o) throw(cannot_have_children);
       Node& operator=(const std::string& contents) throw();
-    private:
+    protected:
       std::string _text;
   };
 
   //----------------------------------------------------------------------------
-  class UnsignedInteger: public Node {
+  class UnsignedInteger: public String {
     public:
-      String(std::string name, const std::string& text = std::string()) throw();
+      UnsignedInteger(std::string name, unsigned long i = 0) throw();
       virtual std::auto_ptr<Node> clone() const throw();
-      virtual ~String() throw() {}
-      virtual std::string text() const throw();
-      virtual String& text(const std::string& txt) throw(tag_expected,
-                                                         type_mismatch);
-      virtual std::ostream& out(std::ostream& o, unsigned int level=0) const
-          throw();
-      virtual String& append(const Node& o) throw(cannot_have_children);
-      Node& operator=(const std::string& contents) throw();
-    private:
-      std::string _text;
+      virtual ~UnsignedInteger() throw() {}
+      virtual UnsignedInteger& text(const std::string& txt)
+          throw(tag_expected, type_mismatch);
+      unsigned long number() const throw();
+      static unsigned long number(const Node& node) throw();
   };
 
   //----------------------------------------------------------------------------
diff --git a/src/xml.cxx b/src/xml.cxx
index cb1741f..1ac02b2 100644
--- a/src/xml.cxx
+++ b/src/xml.cxx
@@ -340,41 +340,43 @@ namespace xml {
   }
 
   //----------------------------------------------------------------------------
-  UnsingedInteger::UnsingedInteger(std::string name, const std::string& text) throw():
-      Node(name), _text(text) {
-  }
-  std::auto_ptr<Node> UnsingedInteger::clone() const throw() {
-    return std::auto_ptr<Node>(new UnsingedInteger(*this));
-  }
-  std::string UnsingedInteger::text() const throw() {
-    return _text;
-  }
-  UnsingedInteger& UnsingedInteger::text(const std::string& txt) throw(tag_expected,
-                                                     type_mismatch) {
-    _text = txt;
-    return *this;
-  }
-  std::ostream& UnsingedInteger::out(std::ostream& o, unsigned int level) const throw() {
-    if (_text.size()) {
-      o<<std::string(level, '\t')<<'<'<<name();
-      for (Attributes::const_iterator it(_attributes.begin());
-           it!=_attributes.end(); ++it)
-        o<<' '<<it->first<<"=\""<<it->second<<'"';
-      o<<'>'<<_text<<"</"<<name()<<'>';
-    } else {
-      o<<std::string(level, '\t')<<'<'<<name();
-      for (Attributes::const_iterator it(_attributes.begin());
-           it!=_attributes.end(); ++it)
-        o<<' '<<it->first<<"=\""<<it->second<<'"';
-      o<<"/>";
+  UnsignedInteger::UnsignedInteger(std::string name, unsigned long i) throw():
+      String(name,
+             dynamic_cast<std::stringstream&>(std::stringstream()<<i).str()) {
+  }
+  std::auto_ptr<Node> UnsignedInteger::clone() const throw() {
+    return std::auto_ptr<Node>(new UnsignedInteger(*this));
+  }
+  UnsignedInteger& UnsignedInteger::text(const std::string& txt)
+      throw(tag_expected, type_mismatch) {
+    std::string::size_type
+      start(txt.find_first_not_of(" \t\n\r")),
+      last(txt.find_last_of(" \t\n\r"));
+    if (start==std::string::npos) { // empty - set to 0
+      _text = "0";
+      return *this;
     }
-    return o;
+    if (txt.find_first_not_of
+        ("0123456789", start,
+         last!=std::string::npos?last-start+1:txt.size()-start)
+        !=std::string::npos)
+      throw type_mismatch(*this, txt,
+                          "unsigned integer may only contain numbers");
+    unsigned long i(0);
+    std::stringstream(txt)>>i;
+    std::stringstream ss;
+    ss<<i;
+    _text = ss.str();
+    return *this;
   }
-  UnsingedInteger& UnsingedInteger::append(const Node& o) throw(cannot_have_children) {
-    throw cannot_have_children(*this, o);
+  unsigned long UnsignedInteger::number() const throw() {
+    return number(*this);
   }
-  Node& UnsingedInteger::operator=(const std::string& contents) throw() {
-    return text(contents);
+  unsigned long UnsignedInteger::number(const Node& node) throw() {
+    unsigned long i(0);
+    std::stringstream ss(node.text());
+    ss>>i;
+    return i;
   }
 
   //----------------------------------------------------------------------------