I guess I wasn't clear on the wildcard, `nForkId=0`

This proposal puts Bitcoin at `nForkId=1`, with the purpose of having 
`nForkId=0` valid on *all* future forks. This means you can create a 
`nLockTime` transaction, delete the private key and still be assured to not 
lose potential future tokens.

In theory `nForkId=0` could be used for an address too, the sending wallet 
should display a warning message about unknown side effects though. This 
address would be future-safe, and you can put it into a safe-deposit box (even 
though I see little reason to back up an _address_. You would always back up a 
_private key_, which translates into funds on any fork.)

Furthermore, `nForkId=0` can be used for L2 applications. Let's say Alice and 
Bob open a payment channel. One week later, project X decides to fork the 
network into a new token, implementing a custom way of providing strong two-way 
replay protection. The protocol Alice and Bob use for the payment channel has 
not implemented this new form of replay protection. Alice and Bob now have to 
make a choice:

(1) Ignore this new token. This comes with an evaluation of how much this new 
token could be worth in the future. They will continue normal channel 
operation, knowing that their funds on the other branch will be locked up until 
eternity. When they close their payment channel, the closing transaction will 
get rejected from the other network, because it's not following the format for 
replay protected transactions.

(2) Close the payment channel before the fork. The transaction, which closes 
the payment channel has to be mined before the fork, potentially paying a 
higher-than-normal fee.

With this proposal implemented, there are two additional choices

(3) Create the commitment transactions with `nForkId=0`. This ensures that when 
the channel gets closed, funds on other chains are released accordingly. This 
also means that after the fork, payments on the channel move both, the original 
token and the new token. Potentially, Alice and Bob want to wait before further 
transacting on the channel, to see if the token has substantial value. If it 
has, they can *then* close the channel and open a new channel again. (Note: The 
funding transaction can use a specific `nForkId`, preventing you from locking 
up multiple coins when funding the channel, but you can choose to settle with 
`nForkId=0` to not lock up future coins)

(4) Make the protocol aware of different `nForkId`. After the fork, the 
participants can chose to *only* close the payment channel on the new token, 
making the payment channel Bitcoin-only again. This is the preferred option, as 
it means no disruption to the original network.

> I like the idea of specifying the fork in bech32 [0]. On the other hand, the 
> standard already has a human readable part. Perhaps the human readable part 
> can be used as the fork id?

I was considering this too. On the other hand, it's only _human readable_ 
because thy bytes used currently encode 'bc'. For future forks, this would just 
be two random letters than, but potentially acceptable.

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