Create bsip-0087.md

bsip-0087.md

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+    BSIP: 0087
+    Title: Force Settlement Fee Ratio
+    Authors:
+      Jerry Liu [email protected]
+    Status: Draft
+    Type: Protocol
+    Created: 2020-02-23
+    Discussion: https://github.com/bitshares/bsips/issues/260
+    Worker: TBD
+
+# Abstract
+This BSIP provide a solution to charge fee from force settlement.
+
+# Motivation
+Force settlement is an important part in smartcoin design, it provides the power to smartcoin holders to ask for collaterals with reference to feed price, and then guarantees the peg of smartcoin.
+
+The community continuously optimize the rules of smartcoin to balance the interests of relevant parties, taking bitCNY as an example, at the beginning the rules focus more on smart coin peg but care less on debt position owners’ interests, change are done to give debt position owners more protection, the force settlement offset has been changed from 0 to 2%, the max settlement  volume per maintenance period has been changed from no limit to 0.5% of smartcoin supply.  
+
+In the past several weeks, force settlement happened more intensively than before, the background is that the crypto market seemly switched from bear to bull, and BTS price went above 0.22CNY - which is the voted threshold per BSIP76, at some time the frequently happened force settlements made the lowest debt position collateral ratio even higher than 3, this phenomenon triggered warm discussion, almost all the users agree that the settler need to pay more cost while executing force settlement, and the cost will be paid to system as fee.
+
+# Rationale
+Force settlement fee can be seen as to pay part of the cost for smartcoin supply, stabilization and also the liquidation of collaterals, it is irrelevant to market fee sharing.
+To ensure the debt positions can always be closed with suffcient smartcoin, it is more feasible to cut off part of the traded collaterals as fee, instead of smartcoin.
+
+# Specification
+Add one new parameter Force Settlement Fee Ratio(FSFR) for each smartcoin, which is controlled by the smartcoin owner.
+`Force settlement order price = settlement price*(1+FSO)/(1-FSFR)`
+
+Here settlement price = feed price.
+
+FSO is Force Settlement Offset.
+
+When a force settlement is executed, the buyer sells smartcoin with quantity `X` and get collaterals in quantity `X*(1-FSFR)/[settlement price*(1+FSO)]`, the settled debt position owner sells collaterals in quantity `X/[settlement price*(1+FSO)]` and get smartcoin in quantity `X`, the delta in paid and received collaterals in quantity `X*FSFR/[settlement price*(1+FSO)]` will be paid to the owner of the smartcoin as force settlement fee.
+
+# Copyright
+This document is placed in the public domain.