use strict;
use warnings;

my $fh;

my $tag;

while(<DATA>){
    chomp;

    if(/^{(.*)}/) {
        $tag = $1;
    } else {
        if($tag eq 'FILE') {
            my $filename = $_;
            print "The filename is $filename\n";
            open($fh, '>', $filename) or die "$filename: $!";
            print $fh '<?xml version="1.0"?>',"\n";
        } elsif(defined($fh)) {
            print $fh "<$tag>$_</$tag>\n";
        }
    }
}
close($fh);
exit(0);

__DATA__
^B^B^B^B^B^B
{FILE}
sourcetag1
{NUMBER}
00000
{SOURCE}
source1
{KEYWORD}
{AUTHOR}
author
staff
{FILE}
sourcetag2
{NUMBER}
00001
{SOURCE}
sourcenam
{KEYWORD}
{AUTHOR}
author1
staff1