<oembed><type>rich</type><version>1.0</version><author_name>npub1m230cem2yh3mtdzkg32qhj73uytgkyg5ylxsu083n3tpjnajxx4qqa2np2</author_name><author_url>https://nostr.ae/npub1m230cem2yh3mtdzkg32qhj73uytgkyg5ylxsu083n3tpjnajxx4qqa2np2</author_url><provider_name>njump</provider_name><provider_url>https://nostr.ae</provider_url><html>📅 Original date posted:2016-11-16&#xA;📝 Original message:On Wed, Nov 16, 2016 at 09:32:24AM -0500, Alex Morcos via bitcoin-dev wrote:&#xA;&gt; I think we are misunderstanding the effect of this change.&#xA;&gt; It&#39;s still &#34;OK&#34; for a 50k re-org to happen.&#xA;&gt; We&#39;re just saying that if it does, we will now have potentially introduced&#xA;&gt; a hard fork between new client and old clients if the reorg contains&#xA;&gt; earlier signaling for the most recent ISM soft fork and then blocks which&#xA;&gt; do not conform to that soft fork before the block height encoded activation.&#xA;&gt; &#xA;&gt; I think the argument is this doesn&#39;t substantially add to the confusion or&#xA;&gt; usability of the system as its likely that old software won&#39;t even handle&#xA;&gt; 50k block reorgs cleanly anyway and there will clearly have to be human&#xA;&gt; coordination at the time of the event.  In the unlikely event that the new&#xA;&gt; chain does cause such a hard fork, that coordination can result in everyone&#xA;&gt; upgrading to software that supports the new rules anyway.&#xA;&gt; &#xA;&gt; So no, I don&#39;t think we should add a checkpoint.  I think we should all&#xA;&gt; just agree to a hard fork that only has a very very slim chance of any&#xA;&gt; practical effect.&#xA;&#xA;So, conceptually, another way to deal with this is to hardcode a blockhash&#xA;where we allow blocks in a chain ending with that blockhash to _not_ follow&#xA;BIP65, up until that blockhash, and any blockchain without that blockhash must&#xA;respect BIP65 for all blocks in the chain.&#xA;&#xA;This is a softfork: we&#39;ve only added rules that made otherwise valid chains&#xA;invalid, and at the same time we are still accepting large reorgs (albeit under&#xA;stricter rules than before).&#xA;&#xA;I&#39;d suggest we call this a exemption hash - we&#39;ve exempted a particular&#xA;blockchains from a soft-forked rule that we would otherwise enforce.&#xA;&#xA;-- &#xA;https://petertodd.org &#39;peter&#39;[:-1]@petertodd.org&#xA;-------------- next part --------------&#xA;A non-text attachment was scrubbed...&#xA;Name: signature.asc&#xA;Type: application/pgp-signature&#xA;Size: 455 bytes&#xA;Desc: Digital signature&#xA;URL: &lt;http://lists.linuxfoundation.org/pipermail/bitcoin-dev/attachments/20161116/eef4afb9/attachment.sig&gt;</html></oembed>