This seems to work fine for me...

my($index, $record) = (0);
while (<$fh>) {
  chomp;
  s/\cM//;
  if (/^(\d)-RECORD$/) {
    $index = $1;
    $record->[$index]->{items} = [];
  }
  elsif (/ITEMNAME-(.*)/) {
    $record->[$index]->{name} = $1;
  }
  elsif (/ITEM \d-(.*)/) {
    push @{$record->[$index]->{items}}, $1;
  }
}
[download]

UPDATE: jeffa pointed out an undef in the record set. that's due to the lack of a 0-RECORD. Ignore it, or do $index = $1 -1, as you will.

--
perl -pew "s/\b;([mnst])/'$1/g"