itās not specific to Indicium. i told you about it here before.
in short,
you issue two kind of tokens A and B based on the same pool of assets (e.g. stocks or cryptos)
On the issuing day peple can buy 1 A or 1 B at $1 price. The money they pay is used to buy underlying assets at current price, and become part of the pool.
After e.g. a year, A holders can redeem and get back $H where H is calculated by Hayekās formula. B holders can redeem at this price
(total_NAV_of_the_pool - H * number_of_outstanding_A) / number_of_outstanding_B
Assuming the NAV never goes 0, A owners always have A at Hayek prices, B tokens price reflects all profit or losses of the pool, including the assets A-holders paid for. Bās price is levered. They get extra return or loss from market volatility.
Actually a can be anything as long as you can sell enough B to absorb volatility so that NAV never is in the red.
In Nu, A is NBT (unchanging price) and B is NSR
in nuLagoon, A is the fixed return pool, B is the turbo return pool.