#!/usr/bin/perl -w

use strict;

my $src = $ARGV[0];
open SRC, "<$src";
my $skip = 0;
while (my $line = <SRC>) {
    if ($line =~ m/datafield tag=""/) {
        $skip = 1;
    }

    if ($skip == 0) {
        $line =~ s/subfield code="""/subfield code="a"/;
        print $line;
    }

    if ($line =~ m/<\/datafield>/) {
        $skip = 0;
    }
}
close SRC;

exit 0;