Update PR 115 (BSIP48) modify_max_supply

bsip-0048.md

@@ -10,45 +10,76 @@
 
 # Abstract
 
-The possibility of creating assets on the BitShares Blockchain is a core feature
-of our platform. In the case of an ico, the ico-holders can create an asset with
-a fixed maximum supply. However this maximum supply can be changed by the
-asset creator (issuer) anytime. This exposes participators ico to the risk,
-of loosing value of their bought asset.
+The possibility of creating assets on the BitShares Blockchain is a core feature of our platform. However some things are too malleable when they should not be. Other things are not flexible when they should be.
 
-With this BSIP a flag will be introduced which forbids the modification of the maximum
-supply of an issuer created asset.
+Asset creators can create an asset with a maximum supply. However this maximum supply can be changed by the asset creator (issuer) anytime. This exposes token holders to the risk of their purchased asset losing value.
+
+With this BSIP a flag will be introduced which forbids the modification of the maximum supply of an issuer created asset.
+
+In addition, another new flag will be introduced that prevents any more tokens from being issued in the future.
+
+And finally, the ability to change the precision of an asset will now be available as long as current supply is zero.
 
 # Motivation
 
-The implementation of a flag, to disable the modification of the maximum supply for 
-issuer created asset, has effects for both sides. On the one side the security for the
-participators or non-issuer users increases, because the value of their assets (tokens)
-can't be manipulated by exposing the market to more created tokens. And on the other side
-it is good marketing for the ico-hoders, because they can advertise with their fixed
-maximum supply.
+A flag to disable the modification of the maximum supply for an asset will be implemented. This has benefits for both the participants and the asset creator. Asset holders are assured the value of their assets (tokens) will not be diluted by issuers creating more tokens. Asset creators are able to market the fact that the maximum supply is fixed.
+
+This can be very important in the case of Initial Coin Offerings (ICOs). Investors are assured by the network that their investment will not be diluted by new supply of that coin.
+
+A flag to disable issuing allows asset holders to be assured that the current supply will not increase, even if there are unissued tokens.
+
+The ability to change the precision of a created asset adds flexibility in the asset creation process.
 
 # Rational
 
-The `disable_modify_max_supply` is a new created flag in the `asset_issuer_permissions`.
-The flag can be activated to forbid the modification of the `max_supply` (`asset_object.options`).
-Once the flag is activated, it can't be deactivated.
+`disable_modify_max_supply` will be added to `asset_issuer_permissions`. The permission can be activated to forbid the modification of the `max_supply` (`asset_object.options`). The related flag can only be set to `false` if `current_supply` is zero.
+
+`disable_issue` will be added to `asset_issuer_permissions`. The permission can be activated to forbid issuance of additional tokens. Once the related flag is set to `true`, it can not be changed.
+
+Changing the precision of an asset should be easily accomplished with an `asset_update_operation`. This causes no harm while the asset is not issued.
 
 # Specifications
 
-This BSIP comes with a change to the protocol, which requires a propotocol upgrade.
-However the changes to the code are minor.
+This BSIP comes with changes to the protocol, hence requires a propotocol upgrade. However the changes to the code are minor.
+
+For `disable_modify_max_supply`:
+
+1. Add `disable_modify_max_supply` to the issuer permissions
+2. Set `disable_modify_max_supply` to false for existing assets at hardfork time
+3. Add a `can_modify_max_supply()` to the `asset_object`
+4. Change the `asset_update_evaluator::do_evaluate` method to assert false for
+    1. the setting of the `disable_modify_max_supply` flag to `false` if `current_supply` is not zero or
+    2. the modification of the `max_supply` when the `disable_modify_max_supply` is `true`
+
+For `disable_issue`:
+
+1. Add `disable_issue` to the issuer permissions
+2. Set `disable_issue` to `false` for existing assets at hardfork time
+3. Add a `can_issue()` to the `asset_object`
+4. Change the `asset_update_evaluator::do_evaluate` method to assert false for the setting of the `disable_issue` flag to `false` if it is currently `true`
+5. Change the `asset_issue_evaluator::do_evaluate` method to assert false if `can_issue()` returns false
+6. Change the `call_order_update_evalutator::do_evaluate` method to assert false if `can_issue()` returns false
+
+To change the precision:
+
+1. Add the `fc::optional<uint8_t> new_precision` to a new `asset_update_operation.extensions` struct.
+2. Change the `asset_update_evaluator::do_evaluate` method to assert false if 
+   1. `new_precision` exists and is not equal to `asset_object.precision` and `current_supply` is not zero
+   2. `new_precision` causes `max_supply` to be an invalid number
+
+# Risks
+
+It is believed that the addition of `disable_modify_max_supply` and `disable_issue` will add security for asset holders.
+
+There is the risk to parties interested in acquiring the asset if the precision is changed after due diligence and before issuance.  
+
+# Discussion
+
+Using `disable_` as names for boolean values is not advisable and can lead to confusion. However, these names were chosen for compatibility reasons. See the comments [of a similar situation here](https://github.com/bitshares/bitshares-core/pull/1375#pullrequestreview-164580457).
 
-1. Add the `disable_modify_max_supply` flag to the issuer permissions
-2. Add a `can_modify_max_supply()` the `asset_object`
-3. Change the `asset_update_evaluator::evaluate` method to assert false for
-    1. the deactivation of the `disable_modify_max_supply` flag
-    2. the modification of the `max_supply` when the `disable_modify_max_supply` is set
-
 # Summary for Shareholders
 
-This BSIP proposes a way to improve the user security in the context of issuer created
-assets.
+This BSIP proposes a way to improve the financial security of users against the dilution of a held asset. It also provides a mechanism for asset creators to modify the precision of their asset.
 
 # Copyright