use of ? in <a href...

I ran across the following in a perl file?
<A HREF=/cgi-bin/gtcom.pl?$user[0]>View Comments</a>
What does the   ?  do?
Is he trying to call the .pl file with an input?
Lee5Asked:
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martinagConnect With a Mentor Commented:
Yes he is.
$user[0] may contain a set of name=value pairs.

gtcom.pl may then parse the input like this:
my ($buffer, @par, $i);
$buffer = "";
$buffer = $ENV{'QUERY_STRING'} if $ENV{'REQUEST_METHOD'} eq 'GET';
read (STDIN, $buffer, $ENV{'CONTENT_LENGTH'}) if $ENV{'REQUEST_METHOD'} eq 'POST';
$buffer =~tr/+/ /;
@par = split /[&=]/, $buffer;
foreach $par (@par) {
      $par =~ s/%([0-9A-F] {2})/chr(hex($1))/egi;
}
for ($i = 0; $i < $#par; $i+=2) {
      if ($form{$par[$i]}) {
            $form{$par[$i]} .= "\n".$par[$i+1];
      }
      else {
            $form{$par[$i]} = $par[$i];
      }
}

The input will be found in %form:
$name = $form{'name'};

Or if it is just a name or something, which means the string will look like this:
"...?martinag"
then will it be read like this:
$name = $ENV{'QUERY_STRING'};

Martin
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