Full-Control Operator Batch Approvals
Your wrapped name is an ERC-1155 NFT that supports the
setApprovalForAll method. When you approve an address using this method, it will have full control over all wrapped ENS names that you own.
This method is typically used by NFT marketplace contracts.
Name-Specific Subname Renewal Manager Approvals
The Name Wrapper also supports the ERC-721
approve method. This method is used to approve a single "Subname Renewal Manager" for a specific name.
The "Renewal Manager" does not have full control over your wrapped name, it can only set / extend the expiry on subnames.
Further, if you burn the CANNOT_APPROVE fuse on your name, then the approved renewal manager can no longer be changed. You can use this to "lock in" that contract, so that you can guarantee to all subname owners that renewals/extensions can always be done.
This approved renewal manager will be reset if the wrapped NFT is burned or re-minted, which happens if you unwrap the name, or if an expired name gets re-registered. It will also be reset if the wrapped NFT is transferred, unless the CANNOT_APPROVE fuse is burned.
Example - Subname Registrar Contract
You can use these operator approval methods to setup a separate contract that can take certain actions on your behalf. One example is setting up a "subname registrar" to allow users to register/renew subnames.
That subname registrar contract would act on your behalf and allow users to register subnames. To allow this, you would call
setApprovalForAll to give that contract full control over your name (and thus the ability to create subnames).
Then, to enable "unruggable renewals", you could call
approve on that same contract (or a separate one specific to renewals if you wish) and burn CANNOT_APPROVE to lock in subname renewals for that contract.
If you need to later on, you would still be able to revoke with
setApprovalForAll. So the contract would lose full control over your name (and the ability to create new subnames), but it would still be able to perpetually renew/extend existing subnames.
And you can do all of this without needing to send your wrapped NFT to that contract.