// call like so:  onKeyPress="return NumberValue(event);"
	function NumberValue(e)
		{
		var key;
		var keychar;
		
		if (window.event)
		   key = window.event.keyCode;
		else if (e)
		   key = e.which;
		else
		   return true;
		keychar = String.fromCharCode(key);
		keychar = keychar.toLowerCase();
		
		// control keys
		if ((key==null) || (key==0) || (key==8) || 
		    (key==9) || (key==13) || (key==27) )
		   return true;
		
		// alphas and numbers
		else if ((("0123456789").indexOf(keychar) > -1))
		   return true;
		else
		   return false;
	}