A hash-of-arrays, e.g.:

>perl -wMstrict -le
"my %STATION_LIST = (
    6 => [ qw/A B C D E F/ ],
    4 => [ qw/A B C D/     ],
   99 => [ qw/foo bar baz/ ],
   );
 ;;
 my $STATION_CNT = 99;
 ;;
 foreach my $stid (@{ $STATION_LIST{$STATION_CNT} }) {
   print qq{station '$stid'};
   }
"
station 'foo'
station 'bar'
station 'baz'
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