Although the constitution is not exactly clear on this, we have historically used a variant of the Borda system (aside from the past two elections) that weighted the lowest-ranked with 0 points. The idea was that in a two-faction election, we would end up with a straight St. Lague allocation of seats. Here's an old post of Ulrika's (back in 2005) where she stated as much:

http://forums.secondlife.com/showthread.php?t=56741

Ulrika posted the equation we used as:

Below is a summary of the results for the vote. As you know, factions were rated from 1 to 3 with more "points" going to those who were higher rated. The equation which calculates the score gives the highest ranked faction a "1" and the lowest ranked faction a "0". Factions in between receive fractional amounts. The equation is

score = (number_of_factions - rank) / (number_of_factions - 1)

Since AFAIK, Ulrika was essentially the SC at that time, I've in the past assumed that this way of counting is constitutional. When we did the first 3-faction elections in 2006, Ulrika raised the counting issue again, and note that in this discussion, we assumed that last place had 0 points:

http://forums.secondlife.com/showthread.php?t=82946

In the Jan 2007 elections, I again reiterated that we used a 0-based counting (with a slight change to use integer rather than fractional counting):

http://forums.slcds.info/viewtopic.php? ... 5231#p5231

So we have here on the one hand historically one way of counting borda scores, and on the other hand a different one based on Jon's more literal interpretation of the constitution (0-based borda scores are unusual, which can possibly be interpreted as not really a borda count; I'm not sure I agree with this, but *shrug*. (note also that 0-based and 1-based ranking do not matter in a winner-take-all environment))

Since Jon prefers 0-based counting, and since we have historically done 0-based counting anyway, I'm going to propose that we use the 0-based count from now on. I think we can do this as regular law (no need for a constitutional amendment) by defining a standard ranking for borda counts in the CDS.