Example:
You have a long position on ETH open and the current ETH/USD price is 1,800. You don't want to close your position below 1,500, so you open a sell stop loss limit order with the stop price set to 1,650, trigger signal is set to “Index” and limit price set to 1,500
The “Index” price falls below 1,650, triggering your stop price. A limit order will then be opened to fill at 1,500(or better).
It is important to note that if any sudden price move was experienced on Kraken only, leading the price to fall below 1,650 while the prevailing market price was above, this “index based” stop limit order would not be triggered. For this order to be triggered, the index price is required to fall below the Stop price set.