Furthermore I realized that I don't understand the ?:, ?=

Perl for Dummies's book said
if for some odd reason you want to suppress $1 or $2 to prevent them from getting assigned, add ?: after the left paranthesis.

example

$test = 'NESTING';
$test =~ /(?:N.)S(.I)/;
print "$1 \n";
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when you run this program, Perl displays "TI"

zak