my @headers;
    my @tmp_split = split /\n/, $post->{post_message};
    foreach (@tmp_split) {

        chomp;
        if ($_ =~ /^\=\=([a-z0-9_ &\[\]ÀÂÄàâäÇçÉÊÈËéêèëÏÌÎïìîÖÔÒöôòÜÛÙ
+üûùA-Z?!;«»()"\s]+)\=\=$/) {

            my $header = $1;

#            print qq|ok, got header of $1<br />\n|;
            my $section = get_section_code($1,$post->{post_message});

            my @tmp_2 = split /\n/, $section;
            my @subheaders;
            foreach my $tmp (@tmp_2) {

#                print qq|checking sub-section for $header, line is: "
+"|
                chomp;
                if ($tmp =~ /^\=\=\=([a-z0-9_ &\[\]ÀÂÄàâäÇçÉÊÈËéêèëÏÌÎ
+ïìîÖÔÒöôòÜÛÙüûùA-Z?!;«»()"\s]+)\=\=\=$/) {    
                    push @subheaders, $1;
                }
            }

            push @headers, { Section => $header, SubLoop => \@subheade
+rs }; 
    
            @subheaders = undef;
            @tmp_2         = undef;

        }


    }
[download]

Sorry, that's because there's a typo in my code :-(

This

   {(?x}
[download]

Should have been this

   {(?x)
[download]