use strict;
use warnings;

my %DB;
my $store = "<Head>";
my $head;

while (<DATA>) {
    if (/.*<B>/ && ! /Last modified/){ #If line is a title
        my $temp = $_;
        $_=~ s/(<[^<>]+>)+//g; chomp;
        if (/\(/){
            $store = $_;
            $DB{$store} = $temp;
        }else{
            $store = $_;
            $DB{$store} = $temp;
        }
    }else{                              #Not a title
    ($store ne "<Head>")? $DB{$store}:$head .= $_;
    }
}

print join "\n", map {"$_ -> $DB{$_}"} keys %DB;

__DATA__
Title line<B>
a line
another line
<Head><B>
this line
that line

##</code><code>##

use strict;
use warnings;

my %DB;
my $store = "<Head>";
my $head;

while (<DATA>) {
    if (/.*<B>/ && ! /Last modified/){ #If line is a title
        my $temp = $_;
        $_=~ s/(<[^<>]+>)+//g; chomp;
        if (/\(/){
            $store = $_;
            $DB{$store} = $temp;
        }else{
            $store = $_;
            $DB{$store} = $temp;
        }
    }else{                              #Not a title
    ($store ne "<Head>")? $DB{$store}:$head .= $_;
    }
}

print join "\n", map {"$_ -> $DB{$_}"} keys %DB;

__DATA__
Title line<B>
a line
another line
<Head><B>
this line
that line