This needs a backward compatibility section (probably simply saying it's n/a).

Also, @achow101 needs to ACK the modifications to BIP 174.

You should add the new type to BIP 174's Appendix A. That should also include a link to the location in the new BIP descriibing it.

@achow101 I added the field to that table. I also mention the BIP in the explanation, but it's currently set to TBD until this BIP gets a number assigned, then I can update both mentions of TBD to become a hyperlink.

@luke-jr added compatibility section.

Assigned BIP 127

I just realized it might be useful to have a way to deal with funds that are locked in a CLTV in the future. Are their opinions about this?

I'm thinking of two approaches:

1. have a global "locktime" variable for the entire proof, which proves that "the prover would be able to spend C coins at time L"
2. allow specifying a locktime for some UTXOs which allows for more fine-grained locktime limitation specification, but might make the "proof statement" more complex. Something like "the prover has ownership of C1 coins now and C2 coins a time L1, ...". For UX purposes the prover can decide to use the same locktime for all it's CLTV UTXOs even though the locktime is further away for some of the UTXOs. Just to simplify the statement.

Both techniques would be quite straightforward to implement for verification.

@luke-jr I updated the files to use the assigned number. Up to you if you merge it like this and allow me to update once I figured out a good way to deal with CLTV or if you want to wait for that in order to merge this.

"the prover would be able to spend C coins at time L"

This can't be proven. The TXOs might get spent before time L.

ACK BIP174 changes

@luke-jr There is an error in the Travis that I don't understand. Seems to be related to the git history. I tried rebasing from latest master but that didn't work..

@luke-jr ping :)

It's saying you need to update the README

@luke-jr fixed the README

I don't currently have much time to work on this, but I think it's quite final apart from the CLTV issue. So can go in like this and I can amend with a fix for that if needed.