Index: CSharpCodeGenerator.cs
===================================================================
--- CSharpCodeGenerator.cs      (revision 70197)
+++ CSharpCodeGenerator.cs      (working copy)
@@ -1376,12 +1376,36 @@
                        return typeOutput;
                }
 
+               static bool is_identifier_start_character (char c)
+                {
+                        return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') || c == '_' || c == '@' || Char.IsLetter (c);
+                }
+
+                static bool is_identifier_part_character (char c)
+                {
+                        return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') || c == '_' || (c >= '0' && c <= '9') || Char.IsLetter (c
)
+;
+                }
+               
                protected override bool IsValidIdentifier (string identifier)
                {
+                       if (identifier == null || identifier.Length == 0)
+                               return false;
+                       
                        if (keywordsTable == null)
                                FillKeywordTable ();
 
-                       return !keywordsTable.Contains (identifier);
+                       if (keywordsTable.Contains (identifier))
+                               return false;
+
+                       if (!is_identifier_start_character (identifier [0]))
+                                return false;
+                        
+                        for (int i = 1; i < identifier.Length; i ++)
+                                if (! is_identifier_part_character (identifier [i]))
+                                        return false;
+                        
+                        return true;
                }
 
                protected override bool Supports (GeneratorSupport supports)