8 to 12 is the neutral equivalent to 2 to 6 on the live side. Basically 1 through 6 are lives (+) and 7 through 12 are neutrals (-).
Simplest terms, just using the live side (+) you have inputs on 1, 3 and 5, outputs on 2, 4 and 6. If a current travels through 1 it is switched to either 2 (on) or 4 (off), 3 is either 2&4 or 4&6 dependent on the switch setup and 5 goes through 4 (off) or 6 (on). This is why pole 4 has no link as all 3 would be switched with a live returning to the other two otherwise. The same applies on the neutral (-) side.
I hope that's a bit clearer.
Lee.