my %main = (   
               'main1' => {'m1sec1'=> ['A','B','C'],},
               'main2' => {'m2sec1'=> ['D','E','F'],},
               'main1-join' => {
                                'm1sec1'=> ['AX','BX','CX',
                                            'AY','BY','CY',
                                            'AZ','AY','AZ'],
                                },                          
                'main2-join' => {
                                 'm2sec1'=> ['DX','EX','FX',
                                             'DY','EY','FY',
                                             'DZ','EZ','FZ], 
                                 }
             );