[Bitcoin-development] BIP62 and future script upgrades

[Peter Todd]

On Tue, Nov 04, 2014 at 12:00:43PM -0800, Pieter Wuille wrote:
> On Tue, Nov 4, 2014 at 11:56 AM, Jeff Garzik <jgarzik at bitpay.com> wrote:
> > On Tue, Nov 4, 2014 at 8:13 PM, Peter Todd <pete at petertodd.org> wrote:
> >> On another topic, I'm skeptical of the choice of nVersion==3 - we'll
> >> likely end up doing more block.nVersion increases in the future, and
> >> there's no reason to think they'll have anything to do with
> >> transactions. No sense creating a rule that'll be so quickly broken.
> >
> > Moderately agreed.
> >
> > Earlier in BIP 62 lifetime, I had commented on ambiguity that arose
> > from bumping tx version simply because we were bumping block version.
> > The ambiguity was corrected, but IMO remains symptomatic of potential
> > problems and confusion down the road.
> >
> > Though I ACK'd the change, my general preference remains to disconnect
> > TX and block version.
> 
> I prefer to see consensus rules as one set of rules (especially
> because they only really apply to blocks - the part for lone
> transactions is just policy), and thus have a single numbering. Still,
> I have no strong opinion about it and have now heard 3 'moderately
> against' comments. I'm fine with using nVersion==2 for transactions.

Keep in mind that we may even have a circumstance where we need to
introduce *two* different new tx version numbers in a single soft-fork,
say because we find an exploit that has two different fixes, each of
which breaks something.

I don't think we have any certainty how new features will be added in
the future - just look at how we only recently realised new opcodes
won't be associated with tx version number bumps - so I'm loath to setup
expectations.

Besides, transactions can certainly be verified for correctness in a
stand-alone fashion outside a block; CHECKLOCKTIMEVERIFY was
specifically designed so that verifying scripts containing it could be
done in a self-contained manner only referencing the transaction the
script was within.

-- 
'peter'[:-1]@petertodd.org
0000000000000000036655c955dd94ba7f9856814f3cb87f003e311566921807
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