A simple solution for STV confusion
Holden Republic and Kiwi Pundit have both commented on the confusion caused by STV voting and, in particular, voting with a mixture of STV and FPP. It occurred to me that there could be a simple solution.
STV only needs a sequence and there is no (mathematical) reason why it shouldn't allow ties. I assume that ballots with 3 candidates marked A 2,B 3,C 10 or A 1, B 2, C 2 (and the remaining candidates unmarked) are currently informal but they needn't be. A 2, B 3, C 10 defines exactly the same ranking as A 1, B 2, C 3. A 1, B 2, C 2 defines a similar ranking but with B and C tied for 2nd. The computer program that counts the results could either randomly break the tie or apportion the vote between the tied parties (or whichever of them are still live). A 1, B 2, C 2 would then count as a vote for A in the first round. If A then drops out the vote becomes 0.5 of a vote each for B and C (if both are still live).
Adopting this system means that ticks can still be counted. A voter who ticks A, B and C and leaves the rest unmarked is simply treated as if he had put a 1 beside each ticked candidate.