diff --git a/common.cpp b/common.cpp
index 96d4d39c..d0effec6 100644
--- a/common.cpp
+++ b/common.cpp
@@ -790,11 +790,21 @@ bool isLower (const string &s)
 
 
 size_t stringNotInSet (const string &s,
-                   	   const string &charSet)
+                   	   const string &charSet,
+                   	   ebool uppercase)
 {
   FFOR (size_t, i, s. size ())
-    if (! charInSet (s [i], charSet))
+  {
+    char c = s [i];
+    switch (uppercase)
+    {
+      case efalse: c = toLower (c); break;
+      case etrue:  c = toUpper (c); break;
+      case enull: break;
+    }
+    if (! charInSet (c, charSet))
       return i;
+  }
   return no_index;
 }
 
@@ -1908,6 +1918,7 @@ void Root::saveFile (const string &fName) const
 
 
 
+#if 0
 void Root::trace (ostream& os,
                   const string& title) const
 { 
@@ -1917,6 +1928,7 @@ void Root::trace (ostream& os,
   os << title << ": ";
   saveText (os);
 }
+#endif
 
 
 
diff --git a/common.hpp b/common.hpp
index 1911f718..603cd635 100644
--- a/common.hpp
+++ b/common.hpp
@@ -116,7 +116,7 @@ constexpr size_t no_index = numeric_limits<size_t>::max ();
 static_assert ((size_t) 0 - 1 == no_index);
 
 constexpr double NaN = numeric_limits<double>::quiet_NaN ();  
-
+  
 
 
 // Global variables
@@ -165,6 +165,11 @@ void beep ();
     
 
 
+template <typename T> 
+  inline bool isNan (T x)
+    { return x != x; }
+
+
 // Comparison templates
 
 template <typename T> 
@@ -465,10 +470,14 @@ template <typename T /*container*/>
 typedef  map<string/*key*/,string/*value*/>  KeyValue;
 
 inline string find (const KeyValue& kv,
-                    const string& key)
+                    const string& key,
+                    bool force)
   { const auto& it = kv. find (key);
     if (it == kv. end ())
+    { if (force)
+        return key;
       throw runtime_error ("Key \"" + key + "\" is not found");
+    }
     return it->second;
   }
 
@@ -725,7 +734,8 @@ inline bool charInSet (char c,
   { return charSet. find (c) != string::npos; }
 
 size_t stringNotInSet (const string &s,
-                   	   const string &charSet);
+                   	   const string &charSet,
+                   	   ebool uppercase);
   // Return: index in s which is not in charSet; may be no_index
 
 size_t strCountSet (const string &s,
@@ -2086,15 +2096,17 @@ struct Root
       saveText (oss);
       return oss. str ();
     }
+#if 0
   void trace (ostream& os,
               const string& title) const;
+#endif
   virtual void saveXml (Xml::File& /*f*/) const 
     { throwf ("Root::saveXml() is not implemented"); }
   virtual Json* toJson (JsonContainer* /*parent_arg*/,
                         const string& /*name_arg*/) const
     { throwf ("Root::toJson() is not implemented"); }
 	virtual bool empty () const
-	  { return true; }
+	  { throwf ("Root::empty() is not implemented"); }
   virtual void clear ()
     { throwf ("Root::clear() is not implemented"); }
     // Postcondition: empty()