I've copied a few posts here to a new thread so as not to take away from Unique's thread about Bonnville. I am not understanding the double-indexes shown and discussed below:
NoPutt, on 26 Sept 2017 - 10:11 AM, said:
shimonko, on 26 Sept 2017 - 11:36 AM, said:
Side question as I'm curious: Does JNPG cater for different hole indexes for 19-36 handicaps than just repeating 1-18, like we have in Aus?
Armand, on 26 Sept 2017 - 12:55 PM, said:
I have no idea on how JNPG hole indexes, but I was going to ask about those higher than 18. I have never seen that before and was wondering what it is all about.
Dazmaniac, on 26 Sept 2017 - 1:46 PM, said:
Do you mean so someone off say 20 knows where to take additional shots?
I'd guess like we do here in UK, where players with handicaps over 18 get 2 shots at the hardest holes up to and including handicap. So play off 20 and you would get 2 shots at SI 1 and 2 and 1 shot at each of the other 16 holes.
I think if you put 20 handicap in the game, it will know where the additional shots are taken as long as the course has SI applied.
shimonko, on 26 Sept 2017 - 3:04 PM, said:
I have a feeling Australia's one of the few places that has the double indexes that you see on the Bonville card.
The theory is that high handicaps definitely need a stroke early on par 3s, but unlikely will need two strokes as there's less opportunity to make a real dog's breakfast of it. You can see on the scorecard above only handicaps around 30 or above get two strokes on the par 3s.
Hmmm ... still not getting it here. 
Are these indexes the player's handicap index or the hole index? I'm used to the hole index being used to rank the holes on each nine as the relative difficulty for a bogey golfer. You seem to be referring the player's handicap index, which I'm struggling to see how that relates to the hole index. I also noted that the ladies index is more conventional - which perhaps adds to my confusion.
jt83, on 27 Sept 2017 - 12:37 AM, said:
Thinking about the split index, how is the normal index a factor at the moment? (I only play individual stroke play.)
It's all about handicapping and the ability for two (or more) players of differing skill levels to play and have a competitive match. I'll do my best to explain it in layman's terms, although you may want to read about it on either:
or, in more general terms:
The player has a "handicap index" which is generally the score of the golfer if they play to their usual ability. This is standardized using the slope and course rating, such that the handicap measures the same golfing ability, regardless if you typically play very difficult or very easy courses. For example, let's assume my handicap is 3.
On most golf courses, each hole is ranked in relative difficulty, with 1 being the "most difficult" and 18 being the "easiest". So with my 3 handicap, the individual hole scores (which are called gross scores) can be reduced by 1 stroke on each of the 3 most difficult holes on the course. The adjustment gives me a "net" score.
In most places, if the player handicap index is over 18 (let's use 20 as an example), then the gross hole score is reduced by one on every hole on the course, and by one more for the two most difficult holes on the course.
For medal/stroke play with one player, the holes where the handicap adjustment is applied doesn't really matter, as your net score will be your gross score less your handicap. When it comes to match play against an opponent, however, the holes where you gross score is reduced by a stroke can/does make a huge difference to the outcome of the match, especially when the players are of different golfing ability (i.e., one player has a handicap index of 2 while the other has one of 10).
The Bonville scorecard confuses me with the use of hole indexes greater than 18. As in my example above, if the player handicap exceeds 18, then you just take another stroke off of the hardest ranked holes. The only explanation I can come up with for the double/split indexes would be that if your handicap is higher than 18, then your next stroke would taken off a designated hole, rather than the hardest ranked hole. To me, that sounds like the hole rankings would not be correct, but perhaps that's because I'm not familiar with the system.
I also can't seem to find anything written about it online anywhere.