Minor adjustment: 

$line =~ /
    ^
    (.+?)
    (?:
        <
        (two|three)
        >
    )?
    $
/xs;

[download]

Another approach: 

my $pre= $line;
my $post= '';
if(  $pre =~ s/
        \s*
        <
        (two|three)
        >
        $
    //xs
) {
    $post= $1;
}

[download]

- tye        

In reply to Re: Regex: Optional/alternative catpures (two) by tye
in thread Regex: Optional/alternative catpures by wfsp

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