That's easy, just add the 'second part':

my $pat1 = qr '(\d-\d\w{2}(?:\.\w+)?)';
my $pat2 = qr '([A-Z]\d{2}(?:\.\d+)?)';
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Concerning grep length, its purpose is simply to filter out empty (and undef) items from the list created by splitting the line on the /$pat1|$pat2/ regex.

hth, dave

Update: Concerning the title line, you say that it 'can be distinguished as it has parenthesis part at the end only'. My tentative regex provides for this. But you also say 'There are some "trash lines" with parenthesis'. Well, what if these "trash lines" actually end with a parenthesised item, eg:

What I meant by 'Better regex' was something to replace the second .+ by something that matches the ID code(?) of your titles. The only two examples you give are B23-9 and A12-3, so perhaps /[A-Z]\d{2}-\d/ would work. Otherwise, adjust accordingly.