[Bitcoin-development] BIP 34: Block v2, Height in Coinbase

Jeff Garzik jgarzik at exmulti.com
Fri Jul 6 16:49:12 UTC 2012

On Fri, Jul 6, 2012 at 12:45 PM, Peter Vessenes <peter at coinlab.com> wrote:
> The proposal is simple, and it's a small change for miners, I imagine.
> My question is: why?
> I worry about stuffing too many requirements on the coinbase. I suppose
> the coinbase is easily extendible if we run out of bytes, but I think I'd
> like to see some more discussion / good / bad type cases for making this
> change. What do we get over just the prev_hash by doing this?

With the existing setup (sans height in coinbase), you might not have
unique transactions, with all that entails.

> Anyway, some background would be great; if I missed it, I'm happy to go
> read up, but I didn't see any links on the wiki.

Gavin wrote some notes on upgrades and BIP16 lessons-learned at

Jeff Garzik
exMULTI, Inc.
jgarzik at exmulti.com

More information about the bitcoin-dev mailing list