my %userData;

open(inData, $data);

while (<inData>) {
    chomp;
    $line = $_;
    if ($line =~/^GC/){
       my $ACTNUM =  substr $line, 11, 9 ;
       my $ref =  substr $line, 0, 3 ;
       $userData{$ACTNUM}{$ref} = $line;
    }
}
for my $ACTNUM (sort keys %userData) {
  $line = $userData{$ACTNUM}{GCA};
  $ACCTNUM = substr $line, 11, 9;
  $FIRM_ID = substr $line, 660, 1;
  $CURR = substr $line, 661, 3;
  print "$CURR,$ACCTNUM,$FIRM_ID\n";
}