Well ... it could be anything but more than likely it's just path info:

#!/usr/bin/perl

use strict;
use warnings;

use CGI;
use Data::Dumper;

my $cgi = CGI->new();

print $cgi->header,
      $cgi->start_html( 'Path Info?' ),
      $cgi->pre( Dumper( $cgi->path_info() ) ),
      $cgi->end_html;
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