ID=1 specifies a length of 1 for the id. That would only allow for 9 groups, 1-9. The next group would be 0 (ID=10), then 1 again (ID=11) and so on. So the SORT on the id wouldn't work correctly. ID=8 specifies a length of 8 for the id. This would allow for 99999999 groups (1-99999999). If you have 9 groups or less, you could use ID=1. If you have more than 9 groups, you'll need a larger length for the ID.