code: protected int sign(Match m, String... ctrlLabel)
  	{
  		int sign = 1;
  
  		for (String lab : ctrlLabel)
  		{
  			Control ctrl = (Control) m.get(lab, getPattern());
  			sign *= sign(ctrl);
  		}
  		return sign;
  	}
docs: Checks the cumulative sign of the chained controls.
  @param m result match
  @param ctrlLabel labels for controls
  @return sign