2020-10-26 Old bitCNY parameters adjustment

[abit]

Purpose:
to restore the peg of bitCNY in the long run and mitigate the issue that some debt positions' collateral ratio is too low.

Changes:
MCR (Maintenance collateral ratio) adjusted from 210% to 220%
Maximum supply adjusted from 25,000,000 to 23,000,000

Current parameters:

ICR (Initial collateral ratio) 315%
MCR (Maintenance collateral ratio) 220%
MSSR (Maximum short-squeeze ratio) 180%
MCFR (Margin call fee rate) 5%
FSO (Force settlement price offset) 2%
FSFP (Force settlement fee percent) 1%

The median feed price is 0.22 CNY/BTS.

Borrowing is enabled. The maximum supply is limited to 23,000,000 bitCNY.


Note:

* As of writing, market trading price of BTS on CEXs is around 0.126 CNY, the collateral ratio (CR) of the debt position with the lowest CR in the BitShares DEX is 120.2%, the corresponding black swan price is 0.105 CNY.

* the ICR value 315% for feed price 0.22 effectively means 180% for market price 0.126, and the corresponding black swan price is 0.070:
0.22 / 315% = 0.126 / 180% = 0.070

* the MCR value 220% for feed price 0.22 effectively means 126% for market price 0.126, and the corresponding black swan price is 0.100:
0.22 / 220% = 0.126 / 126% = 0.100

* the MSSR value 180% for feed price 0.22 means collateral of low-CR debt positions will be listed for sale at 0.22 / 180% = 0.122 bitCNY
** the MCFR value 5% means the price for buyers' is 0.22 / (180%-5%) = 0.1257143 bitCNY
** 0.122 / 0.126 = 96.8% which means the actual penalty for being margin called is 3.2%