Active bans are all your bans that expires within the last 12 months. Active history bans are those that are extended due to history and have expired within the last 12 months.
Rule 2.8 answers this one:
"The first 3 bans are issued at the staff member’s discretion"
If you have 4 inactive bans the new ban will be according to:
"The first 3 bans are issued at the staff members discretion"
Hope that clears it up