There's another important use case which you mentioned Greg, that also requires special exemption: compact commitments via mid-state compression. The use case is an OP_RETURN output sorted last, whose last N bytes are a commitment of some kind. A proof of the commitment can then use mid state compression to elide the beginning of the transaction. How do you make a special exemption for this category of outputs? I can't think of a very clean way of doing so that doesn't require an ugly advertising of sort-order exemptions. The fact that we have two different existing use cases which conflict with soft-fork enforcement, I'm quiet concerned that there are either other things we aren't thinking of or haven't invented yet which would be affected. On Sun, Jun 14, 2015 at 7:33 PM, Gregory Maxwell wrote: > On Mon, Jun 15, 2015 at 2:29 AM, Rusty Russell > wrote: > > The softfork argument I find the most compelling, though it's tempting > > to argue that every ordering use (including SIGHASH_SINGLE) is likely > > a mistake. > > Oh. > > Hm. > > It is the case that the generalized sighash flag design I was thinking > about was actually completely neutral about ordering, and yet still > replaced SINGLE. > > I need to think a bit on that. > > > ------------------------------------------------------------------------------ > _______________________________________________ > Bitcoin-development mailing list > Bitcoin-development@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/bitcoin-development >