Access Control List (ACL)

An approval layer for creating, updating, or deleting streams on another user’s behalf.
The Access Control List (ACL) allows any account (plain EOA or contract) to configure permissions for another account to create/update/delete streams on its behalf.
It's basically the money streaming equivalent of the ERC20 approval mechanism!
allowance, approval, and transferFrom are to ERC20 transfers as getFlowOperatorData, updateFlowOperatorPermissions, and (create/update/delete)FlowByOperator are to Superfluid streams.
If you're checking out the functions ACL provides you, you'll want to understand the flowRateAllowance and permissions parameters.

flowRateAllowance Parameter

You can think of flowRateAllowance as a tank. When you set flowRateAllowance in your updateFlowOperatorPermissions call imagine you've filled up that tank to a level of your choosing for the flowOperator account.
ThatflowOperator account can spend its flowRateAllowance tank as it likes. Every time it increases a flow rate on your behalf, its flowRateAllowance tank is depleted by the amount of the increase.
On the other side, actions that decrease your flow rate (updating a stream to a lower flow rate or deleting one) don't affect flowRateAllowance.
If a flowOperator's flowRateAllowance is too small for it to create/increase a flow, then its action is reverted. This entire dynamic is just like the ERC20 allowance mechanism! Here's an example to drive it home 👇
Let’s assume that we enable an operator to create and update streams with a flowRate allowance of 1000 tokens per month (which would be represented as a flow rate of 385802469135802 tokens per second). If our operator creates a stream on our behalf with a flowRate of 500 tokens per month, then the operator’s remaining flowRateAllowance becomes 500 tokens per month (1000/month - 500/month). Then, if our operator updates another one of our streams that is already outstanding by increasing our flowRate by 250 tokens per month, then our operator’s flowRateAllowance will decrease by another 250 tokens per month, leaving the remaining flowRateAllowance at 250 tokens per month (500/month - 250/month).

permissions Parameter

The permissions value is a uint256 from 1 to 7 representing a specific level of access that an operator gets over your streams. You pass in permissions when calling updateFlowOperatorPermissions.
Permission Type
Parameter Value
Create or Update
Create or Delete
Delete or Update
Create, Update, or Delete