defined $opt{1} and read_structure_type1($opt{1});
defined $opt{2} and read_structure_type2($opt{2});
read_structure_type3($opt{3}) if defined $opt{3};

defined $opt{f} and do{ $fldname = $opt{f} };            
$length   = $opt{l} if defined $opt{l};
$location = defined $opt{L} ? $opt{L} : 'default';
$infile   = $opt{i} || 'default';
$dirname  = $opt{d} || '/dev/null';

do {usage(); exit; } if defined $opt{h} or not %opt;