ColumnReferenceExpression( String rowInd, int columnIndex )
ColumnReferenceExpression( String rowInd, String columnName )
	ColumnReferenceExpression( String rowInd, int columnIndex )	{		logger.entering( ColumnReferenceExpression.class.getName( ),				"ColumnReferenceExpression",				new Integer( columnIndex ) );		assert( columnIndex >= 0 );		m_columnIndex = columnIndex;		rowIndicator = rowInd;		logger.exiting( ColumnReferenceExpression.class.getName( ),				"ColumnReferenceExpression" );	}