elsif ( /^ \s+ ( \S{13} \s+ \S+ \s+ \S.* )/x ) {
    my @fields = unpack "a21 a9 a9 a2 a13 a8 a9 a9 a4 a5 a6", $1;
    # ...
}

##</code><code>##

elsif ( /^ \s+ ( \S{13} \s+ \S+ \s+ \S.* )/x ) {
    my @field = qw(
        PIIN  FSCM  N/A   U/I  UNIT  PRICE  AWD
        DT    QTY   OPT   DT   FOB   REP    TYPE
    );
    my %value;
    @value{ @field } = unpack "a21 a9 a9 a2 a13 a8 a9 a9 a4 a5 a6", $1;
    printf "      %-10s = %s\n", $_, $value{ $_ } for @field;
    print "\n";
}