{"type":"rich","version":"1.0","author_name":"npub1azvhdrf9fu6n0tm7yez4j6zcxcedp2ct6nrcq3z74naqs7kgpk8s5t2krq","author_url":"https://nostr.ae/npub1azvhdrf9fu6n0tm7yez4j6zcxcedp2ct6nrcq3z74naqs7kgpk8s5t2krq","provider_name":"njump","provider_url":"https://nostr.ae","html":"📅 Original date posted:2015-11-25\n📝 Original message:As I said in an earlier post, a systems developer and an application \ndeveloper have very different perspectives on this. From the former's \nperspective, it is entirely sensible to name things based on basic \nfeatures of the system's design (i.e. a field in the txin or tx that \ngets checked) - but from an app developer's perspective, what matters is \nhow they will use a particular feature in an actual app.\n\nI think that part of what systems developers should strive to do is to \nabstract out the inner minutiae of the system's guts and expose to app \ndevelopers the clearest interface with which to develop apps. This is \neven more the case when the details of the inner workings are completely \nirrelevant to the application logic and there's no real gains to be had \nfrom attempting to optimize for the inner workings when designing an \napplication.\n\n\u003eFrom an app developer's perspective, I think it is pretty blatantly \nclear that relative timelock is *the* critical exposed functionality \nintended here. Now, one could argue that the satoshi script is still a \nsystems level component of the system...but with the advent of overlay \nprotocols such as payment channels and the Lightning Network, it is \nclear that we now require a new abstraction layer for reasoning about \nthe higher level logic of the system that doesn't burden the protocol \ndesigner with having to know the intimate and esoteric details of the \nlower system levels. Of course, many of those who work on these higher \nlevel protocols will also be experts in the underlying system design. \nHowever, it greatly increases the learning curve and can easily \nfrustrate people looking to work on these ideas...and ultimately, \nknowing the inner details of how the nSequence field is structured and \nwhat the bits actually mean is irrelevant to someone trying to design \nscripts for such applications.\n\nWe've already deployed another opcode, CHECKLOCKTIMEVERIFY, which does \nrefer to the field name. However, in this particular situation, the \nfield name reflects *far* more closely what the app developer actually \ncares about than nSequence, which to the app developer might as well be \ncalled foo. As such, I stick with my original vote - we should call the \nopcode RCHECKLOCKTIMEVERIFY, which has the advantage of communicating \nfairly directly to developers and protocol designers the semantics they \nactually care about and also makes clear the relationship between \nabsolute and relative timelock...that's to say, the ability for the \nscript designer to lock specific coins until either a specific moment in \ntime or until a certain delay has passed since the coin output was \ncreated (added to blockchain).\n\nLet's face it - the entire motivation behind BIP68/BIP112 is relative \ntimelock. Explicitly calling the opcode RCHECKLOCKTIMEVERIFY will make \nlife easier for everyone and will help sell the idea and help it gain \ngreater acceptance more quickly; while stubbornly adhering to an \nesoteric detail that is only there for historical reasons will only \ncontinue to delay the idea's acceptance and adoptance.\n\n- Eric\n\n------ Original Message ------\nFrom: \"Mark Friedenbach via bitcoin-dev\" \n\u003cbitcoin-dev at lists.linuxfoundation.org\u003e\nTo: \"Btc Drak\" \u003cbtcdrak at gmail.com\u003e\nCc: \"Bitcoin Dev\" \u003cbitcoin-dev at lists.linuxfoundation.org\u003e\nSent: 11/25/2015 3:05:50 PM\nSubject: Re: [bitcoin-dev] Alternative name for CHECKSEQUENCEVERIFY \n(BIP112)\n\n\u003eLooks like I'm the long dissenting voice here? As the originator of the \n\u003ename CHECKSEQUENCEVERIFY, perhaps I can explain why the name was \n\u003eappropriately chosen and why the proposed alternatives don't stand up.\n\u003e\n\u003eFirst, the names are purposefully chosen to illustrate what they do:\n\u003e\n\u003eWhat does CHECKLOCKTIMEVERIFY do? It verifies the range of \n\u003etx.nLockTime.\n\u003eWhat does CHECKSEQUENCEVERIFY do? It verifies the range of \n\u003etxin.nSequence.\n\u003e\n\u003eSecond, the semantics are not limited to relative lock-time / maturity \n\u003eonly. They both leave open ranges with possible, but currently \n\u003eundefined future consensus-enforced behavior. We don't know what sort \n\u003eof future behavior these values might trigger, but the associated \n\u003eopcodes are generic enough to handle them:\n\u003e\n\u003eCHECKLOCKTIMEVERIFY will pass an nSequence between 1985 and 2009, even \n\u003ethough such constraints have no meaning in Bitcoin.\n\u003eCHECKSEQUENCEVERIFY is explicitly written to permit a 5-byte push \n\u003eoperand, while checking only 17 of the available 39 bits of both the \n\u003eoperand and the nSequence. Indeed the most recent semantic change of \n\u003eCSV was justified in part because it relaxes all constraints over the \n\u003evalues of these bits freeing them for other purposes in transaction \n\u003evalidation and/or future extensions of the opcode semantics.\n\u003e\n\u003eThird, single-byte opcode space is limited. There are less than 10 such \n\u003eopcodes left. Maybe space won't be so precious in a post-segwitness \n\u003eworld, but I don't want to presume that just yet.\n\u003e\n\u003e\n\u003eAs for the alternatives, they capture only the initial use case of \n\u003enSequence. My objection would relax if nSequence were renamed, but I \n\u003ethink that would be too disruptive and unnecessary. In any case, the \n\u003eimagined use cases for CHECKSEQUENCEVERIFY has to do with sequencing \n\u003eexecution pathways of script, so it's not a stretch in meaning. \n\u003ePreviously CHECKMATURITYVERIFY was a hypothicated opcode that directly \n\u003echecked the minimum age of inputs of a transaction. The indirect naming \n\u003eof CHECKSEQUENCEVERIFY on the other hand is due to its indirect \n\u003ebehavior. RELATIVELOCKTIMEVERIFY was also a hypothicated opcode that \n\u003ewould check a ficticious nRelativeLockTime field, which does not exist. \n\u003eAgain my objection would go away if we renamed nSequence, but I \n\u003eactually think the nSequence name is better...\n\u003e\n\u003eOn Tue, Nov 24, 2015 at 2:30 AM, Btc Drak via bitcoin-dev \n\u003e\u003cbitcoin-dev at lists.linuxfoundation.org\u003e wrote:\n\u003e\u003eBIP68 introduces relative lock-time semantics to part of the nSequence \n\u003e\u003efield leaving the majority of bits undefined for other future \n\u003e\u003eapplications.\n\u003e\u003e\n\u003e\u003eBIP112 introduces opcode CHECKSEQUENCEVERIFY (OP_CSV) that is \n\u003e\u003especifically limited to verifying transaction inputs according to \n\u003e\u003eBIP68's relative lock-time[1], yet the _name_ OP_CSV is much boarder \n\u003e\u003ethan that. We spent months limiting the number of bits used in BIP68 \n\u003e\u003eso they would be available for future use cases, thus we have \n\u003e\u003eacknowledged there will be completely different usecases that take \n\u003e\u003eadvantage of unused nSequence bits.\n\u003e\u003e\n\u003e\u003eFor this reason I believe the BIP112 should be renamed specifically \n\u003e\u003efor it's usecase, which is verifying the time/maturity of transaction \n\u003e\u003einputs relative to their inclusion in a block.\n\u003e\u003e\n\u003e\u003eSuggestions:-\n\u003e\u003e\n\u003e\u003eCHECKMATURITYVERIFY\n\u003e\u003eRELATIVELOCKTIMEVERIFY\n\u003e\u003eRCHECKLOCKTIMEVERIFY\n\u003e\u003eRCLTV\n\u003e\u003e\n\u003e\u003eWe could of course softfork additional meaning into OP_CSV each time \n\u003e\u003ewe add new sequence number usecases, but that would become obscure and \n\u003e\u003econfusing. We have already shown there is no shortage of opcodes so it \n\u003e\u003emakes no sense to cram everything into one generic opcode.\n\u003e\u003e\n\u003e\u003eTL;DR: let's give BIP112 opcode a name that reflects it's actual \n\u003e\u003eusecase rather than focusing on the bitcoin internals.\n\u003e\u003e\n\u003e\u003e[1] \n\u003e\u003ehttps://github.com/bitcoin/bitcoin/pull/6564/files#diff-be2905e2f5218ecdbe4e55637dac75f3R1223\n\u003e\u003e\n\u003e\u003e_______________________________________________\n\u003e\u003ebitcoin-dev mailing list\n\u003e\u003ebitcoin-dev at lists.linuxfoundation.org\n\u003e\u003ehttps://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev\n\u003e\u003e\n\u003e\n-------------- next part --------------\nAn HTML attachment was scrubbed...\nURL: \u003chttp://lists.linuxfoundation.org/pipermail/bitcoin-dev/attachments/20151125/180fa442/attachment.html\u003e"}