private static GregorianCalendar getDateFromPtg( Ptg op )
	{
		Object o;
		if( op instanceof PtgStr )
		{
			o = calcDateValue( new Ptg[]{ op } ).getValue();
		}
		else if( op instanceof PtgRef )
		{
			o = op.getValue();
			if( o instanceof String )
			{
				o = calcDateValue( new Ptg[]{ new PtgStr( o.toString() ) } ).getValue();
			}
		}
		else if( op instanceof PtgName )
		{
			o = op.getValue();    //getComponents()[0];
			o = op.getValue();
			if( o instanceof String )
			{
				o = calcDateValue( new Ptg[]{ new PtgStr( o.toString() ) } ).getValue();
			}
		}
		else
		{
			o = op.getValue();
		}

		return (GregorianCalendar) DateConverter.getCalendarFromNumber( o );
	}