my %record;
my ( $id, $field );
while (<>) {
    chomp;
    if ( /^RECORD:\s+(\d+)/ ) {
        $id = $1;
    elsif ( /Field:\s/ ) {
        $field = $_;
    elsif ( /MSG#\s ) {
        $record{$id}{field} = $field;
        $record{$id}{msg} = $_;
    }
}
# now go through the %record set, output to csv...