my %records;
my $record;

while (<DATA>) {
   chomp;

   my $line = $_;
   s/^(\d\d)//;
   my $subrecord_type = $1;

   if ($subrecord_type == 10) {
      s/^(\d+)\s+//;
      my $procedure_num = $1;
      $records{$procedure_num} = $record = [];
   }

   push(@$record, $line);
}

require Data::Dumper;
print(Data::Dumper::Dumper(\%records));

__DATA__
1000001 01.11.199600.00.00001 A1 1 SN Y
2001.11.200400098.0500073.5500083.35
5001.11.1997Professional attendance being an attendance at
5001.11.1997other than consulting rooms, by a general
5001.11.1997practitioner on not more than 1 patient


output
======

$VAR1 = {
          '00001' => [
                       '1000001 01.11.199600.00.00001 A1 1 SN Y',
                       '2001.11.200400098.0500073.5500083.35',
                       '5001.11.1997Professional attendance being an attendance at',
                       '5001.11.1997other than consulting rooms, by a general',
                       '5001.11.1997practitioner on not more than 1 patient',
                     ]
        };