diff --git a/prism/src/chart/ChartException.java b/prism/src/chart/ChartException.java
new file mode 100644
index 00000000..478a301e
--- /dev/null
+++ b/prism/src/chart/ChartException.java
@@ -0,0 +1,38 @@
+//==============================================================================
+//	
+//	Copyright (c) 2002-2006, Dave Parker
+//	
+//	This file is part of PRISM.
+//	
+//	PRISM is free software; you can redistribute it and/or modify
+//	it under the terms of the GNU General Public License as published by
+//	the Free Software Foundation; either version 2 of the License, or
+//	(at your option) any later version.
+//	
+//	PRISM is distributed in the hope that it will be useful,
+//	but WITHOUT ANY WARRANTY; without even the implied warranty of
+//	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+//	GNU General Public License for more details.
+//	
+//	You should have received a copy of the GNU General Public License
+//	along with PRISM; if not, write to the Free Software Foundation,
+//	Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+//	
+//==============================================================================
+
+package chart;
+
+public class ChartException extends Exception
+{
+	public ChartException(String s)
+	{
+		super(s);
+	}
+	
+	public String toString()
+	{
+		return "Error: " + getMessage() + ".";
+	}
+}
+
+//------------------------------------------------------------------------------