This motion pretty explicitly spells this out.
Currently, we count NuSafe as BTC. If we grow our stable reserves like tether, eventually we will sell all our BTC for NSR because our stable reserves will be over 15%, and we will enter a weird negative BTC state that doesn’t make sense.
Once this motion passes, we count stable liquidity like NuSafe as negative NBT for the purposes of calculating outstanding NBT. Then, the 15% is pure BTC. As a consequence, PPC and other dynamic reserves would also take into account stable reserves when calculating overflow.
This motion reduces buybacks in favor of a more logical form of accounting that won’t result in us holding negative BTC amounts. It is not ‘on top of’, it is a coupled relationship.
Imagine we hold $500,000 stable liquidity and there are 1 million nbt in circulation. That would mean we would want $75,000 in btc. Without this motion we would have to hold -$350,000 (that’s negative) which wouldnt make sense. If it were on top of, we would need $150,000 in btc.