Essentially what the perl compiler does with heredocs is to replace the heredoc definition with a string equivalent of the contents of the heredoc. By runtime, the heredoc itself is gone. If you do this yourself, mentally, then you will see that:

my $text = <<"EOT"
This
is
my
text.
EOT
;
[download]

and

my $text = <<"EOT";
This
is
my
text.
EOT
[download]

are identical, and equal to:

my $text = "This\nis\nmy\ntext.\n";
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Update: BTW, this lets you do weird things like this:

while ( <<"EOT" =~ m/(.*is.*)/g )
This
is
my
text,
isn't it?
EOT
{
    print $1,"\n";
}
[download]

Impossible Robot