Meek's version of the Single Transferable Vote system [.pdf] is used in multiple big elections including those of New Zealand and Stack Exchange.
Demonstration (with thanks to the Department of Internal Affairs of New Zealand).
I have a basic understanding of how the votes are counted, but there's one thing I haven't been able to figure out.
What happens if positions are left blank?
For example: Assume 6 candidates and no limit on the amount of choices.
One could vote (where left is first vote and right is last):
3 4 5 6 1 2 or
4 5 6 and leave the rest blank.
In the STV system, the following is legal as well:
0 2 4 0 1 6
What would happen in that case?
Will the choices be shifted to clear it from any left-open positions or will the votes be counted at the moment indicated by the position? Those options will (likely) influence the election both in different ways.
I'm not a CS expert in any way, just trying to get the hang of an interesting system to implement my own vote counter.