Quote from: tspacepilot on July 22, 2017, 06:38:21 AM

Quote from: junan1 on July 22, 2017, 03:12:04 AM

BIP 9 ("version bits") is a standard for proposing Bitcoin upgrades or "deployments". Code for this is included in Bitcoin Core.
BIP 141, together with BIP 143 and BIP 147, ("SegWit") is a deployment which follows the BIP 9 standard. Code for this is included in Bitcoin Core.
BIP 91 ("SegSignal") is a deployment which uses the BIP 9 machinery while not strictly following the standard. Code for this is not included in Bitcoin Core but is included in a fork of Bitcoin Core called "btc1".

By modifying the version field in the block header, miners can "signal" their support for any combination of deployments. Bit 1 of the version field corresponds to SegWit and bit 4 corresponds to SegSignal.

https://blockchain.info/charts/bip-9-segwit charts the signalling of SegWit (bit 1) where each datapoint is in fact the average signalling rate of the prior 2016 blocks (~ 2 weeks). However, as you rightly observe, there has been a recent increase in SegWit signalling. Of the last 144 blocks (~ 1 day), 131 have signaled for SegWit (~ 91%). If the 2016-block moving average chart is at 95% or higher at a difficulty change then SegWit will "lock in".

That's really clear, junan1, thanks. I appreciate "SegSignal" as a name instead of numbers, which are easier to mix up.

Thank you tspacepilot. Note: "segsignal" is the name given to this deployment by the author of BIP 91, James Hilliard.

Quote from: tspacepilot on July 22, 2017, 06:38:21 AM

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SegSignal is already locked in and all nodes following SegSignal will consider invalid any blocks at height 477120 or greater (~ 2017-07-23, 8:00am UTC). Note again that Bitcoin Core does not include code for this deployment (hence the warnings) and so Bitcoin Core will not reject blocks as SegSignal requires.

I understand that it's also a theoretical possibility that those who are currently sending SegSignal may not actually follow through and orphan non-segwit blocks. But I understand that we expect them to do so.

Yes, I wasn't too clear here. All nodes (miners or otherwise) following the rules of BIP 91 (adopting SegSignal) will consider invalid any blocks which do not signal SegWit when this deployment becomes active. However, there's nothing preventing nodes from giving up on SegSignal at any time. Additionally, there's nothing preventing miners from setting bit 4 whether or not they intend to adopt SegSignal.

Technically, the same applies to SegWit itself.