Eep, sorry.
PPI is (originally) short for Parse::Perl::Isolated. It parses perl as a Document, without using perl itself.
The "Signficicant Tokens" metric ignores lines, variable name lengths, string length, POD and just goes on the complexity of the code itself, and can be found using something like the following.
use PPI;
# Load a perl document
my $Document = PPI::Document->load( 'mycode.pl' );
my $significant = grep { ! $_->significant } $Document->tokens;