[[appdxbitcoinimpproposals]]
[appendix]
== Bitcoin Improvement Proposals

Bitcoin Improvement Proposals are design documents providing information to the Bitcoin community, or for describing a new feature for Bitcoin or its processes or environment.

As per BIP1 _BIP Purpose and Guidelines_, there are three((("Bitcoin Improvement Proposals (BIPs)", "types of"))) kinds of BIPs:

_Standard_ BIP:: Describes any change that affects most or all Bitcoin implementations, such as a change to the network protocol, a change in block or transaction validity rules, or any change or addition that affects the interoperability of applications using Bitcoin.
_Informational_ BIP:: Describes a Bitcoin design issue, or provides general guidelines or information to the Bitcoin community, but does not propose a new feature. Informational BIPs do not necessarily represent a Bitcoin community consensus or recommendation, so users and implementors may ignore informational BIPs or follow their advice.
_Process_ BIP:: Describes a Bitcoin process, or proposes a change to (or an event in) a process. Process BIPs are like standard BIPs but apply to areas other than the Bitcoin protocol itself. They might propose an implementation, but not to Bitcoin's codebase; they often require community consensus; and unlike informational BIPs, they are more than recommendations, and users are typically not free to ignore them. Examples include procedures, guidelines, changes to the decision-making process, and changes to the tools or environment used in Bitcoin development. Any meta-BIP is also considered a process BIP.

BIPs are recorded in a https://oreil.ly/jjO0R[versioned repository on GitHub].
An MIT-licensed document from the open source Bitcoin Core project,
reproduced here in edited form, describes which BIPs it implements, including listing
the Pull Request (PR) and version of Bitcoin Core where support for each BIP was added or
significantly changed.

BIPs that are implemented by Bitcoin Core:

-    BIP9: The changes allowing multiple soft-forks to be deployed in parallel have been implemented since v0.12.1 (PR #7575)
-    BIP11: Multisig outputs are standard since v0.6.0 (PR #669).
-    BIP13: The address format for P2SH addresses has been implemented since v0.6.0 (PR #669).
-    BIP14: The subversion string is being used as User Agent since v0.6.0 (PR #669).
-    BIP16: The pay-to-script-hash evaluation rules have been implemented since v0.6.0, and took effect on April 1st 2012 (PR #748).
-    BIP21: The URI format for Bitcoin payments has been implemented since v0.6.0 (PR #176).
-    BIP22: The 'getblocktemplate' (GBT) RPC protocol for mining has been implemented since v0.7.0 (PR #936).
-    BIP23: Some extensions to GBT have been implemented since v0.10.0rc1, including longpolling and block proposals (PR #1816).
-    BIP30: The evaluation rules to forbid creating new transactions with the same txid as previous not-fully-spent transactions were implemented since v0.6.0, and the rule took effect on March 15th 2012 (PR #915).
-    BIP31: The 'pong' protocol message (and the protocol version bump to 60001) has been implemented since v0.6.1 (PR #1081).
-    BIP32: Hierarchical Deterministic Wallets has been implemented since v0.13.0 (PR #8035).
-    BIP34: The rule that requires blocks to contain their height (number) in the coinbase input, and the introduction of version 2 blocks has been implemented since v0.7.0. The rule took effect for version 2 blocks as of block 224413 (March 5th 2013), and version 1 blocks are no longer allowed since block 227931 (March 25th 2013) (PR #1526).
-    BIP35: The 'mempool' protocol message (and the protocol version bump to 60002) has been implemented since v0.7.0 (PR #1641). As of v0.13.0, this is only available for NODE_BLOOM (BIP111) peers.
-    BIP37: The bloom filtering for transaction relaying, partial Merkle trees for blocks, and the protocol version bump to 70001 (enabling low-bandwidth lightweight clients) has been implemented since v0.8.0 (PR #1795). Disabled by default since v0.19.0, can be enabled by the -peerbloomfilters option.
-    BIP42: The bug that would have caused the subsidy schedule to resume after block 13440000 was fixed in v0.9.2 (PR #3842).
-    BIP43: The experimental descriptor wallets introduced in v0.21.0 by default use the Hierarchical Deterministic Wallet derivation proposed by BIP43. (PR #16528)
-    BIP44: The experimental descriptor wallets introduced in v0.21.0 by default use the Hierarchical Deterministic Wallet derivation proposed by BIP44. (PR #16528)
-    BIP49: The experimental descriptor wallets introduced in v0.21.0 by default use the Hierarchical Deterministic Wallet derivation proposed by BIP49. (PR #16528)
-    BIP61: The 'reject' protocol message (and the protocol version bump to 70002) was added in v0.9.0 (PR #3185). Starting v0.17.0, whether to send reject messages can be configured with the -enablebip61 option, and support is deprecated (disabled by default) as of v0.18.0. Support was removed in v0.20.0 (PR #15437).
-    BIP65: The CHECKLOCKTIMEVERIFY softfork was merged in v0.12.0 (PR #6351), and backported to v0.11.2 and v0.10.4. Mempool-only CLTV was added in PR #6124.
-    BIP66: The strict DER rules and associated version 3 blocks have been implemented since v0.10.0 (PR #5713).
-    BIP68: Sequence locks have been implemented as of v0.12.1 (PR #7184), and have been buried since v0.19.0 (PR #16060).
-    BIP70 71 72: Payment Protocol support has been available in Bitcoin Core GUI since v0.9.0 (PR #5216). Support can be optionally disabled at build time since v0.18.0 (PR 14451), and it is disabled by default at build time since v0.19.0 (PR #15584). It has been removed as of v0.20.0 (PR 17165).
-    BIP84: The experimental descriptor wallets introduced in v0.21.0 by default use the Hierarchical Deterministic Wallet derivation proposed by BIP84. (PR #16528)
-    BIP86: Descriptor wallets by default use the Hierarchical Deterministic Wallet derivation proposed by BIP86 since v23.0 (PR #22364).
-    BIP90: Trigger mechanism for activation of BIPs 34, 65, and 66 has been simplified to block height checks since v0.14.0 (PR #8391).
-    BIP111: NODE_BLOOM service bit added, and enforced for all peer versions as of v0.13.0 (PR #6579 and PR #6641).
-    BIP112: The CHECKSEQUENCEVERIFY opcode has been implemented since v0.12.1 (PR #7524), and has been buried since v0.19.0 (PR #16060).
-    BIP113: Median time past lock-time calculations have been implemented since v0.12.1 (PR #6566), and has been buried since v0.19.0 (PR #16060).
-    BIP125: Opt-in full replace-by-fee signaling partially implemented. See doc/policy/mempool-replacements.md.
-    BIP130: direct headers announcement is negotiated with peer versions >=70012 as of v0.12.0 (PR 6494).
-    BIP133: feefilter messages are respected and sent for peer versions >=70013 as of v0.13.0 (PR 7542).
-    BIP141: Segregated Witness (Consensus Layer) as of v0.13.0 (PR 8149), defined for mainnet as of v0.13.1 (PR 8937), and buried since v0.19.0 (PR #16060).
-    BIP143: Transaction Signature Verification for Version 0 Witness Program as of v0.13.0 (PR 8149), defined for mainnet as of v0.13.1 (PR 8937), and buried since v0.19.0 (PR #16060).
-    BIP144: Segregated Witness as of 0.13.0 (PR 8149).
-    BIP145: getblocktemplate updates for Segregated Witness as of v0.13.0 (PR 8149).
-    BIP147: NULLDUMMY softfork as of v0.13.1 (PR 8636 and PR 8937), buried since v0.19.0 (PR #16060).
-    BIP152: Compact block transfer and related optimizations are used as of v0.13.0 (PR 8068).
-    BIP155: The 'addrv2' and 'sendaddrv2' messages which enable relay of Tor V3 addresses (and other networks) are supported as of v0.21.0 (PR 19954).
-    BIP157 158: Compact Block Filters for Light Clients can be indexed as of v0.19.0 (PR #14121) and served to peers on the P2P network as of v0.21.0 (PR #16442).
-    BIP159: The NODE_NETWORK_LIMITED service bit is signalled as of v0.16.0 (PR 11740), and such nodes are connected to as of v0.17.0 (PR 10387).
-    BIP173: Bech32 addresses for native Segregated Witness outputs are supported as of v0.16.0 (PR 11167). Bech32 addresses are generated by default as of v0.20.0 (PR 16884).
-    BIP174: RPCs to operate on Partially Signed Bitcoin Transactions (PSBT) are present as of v0.17.0 (PR 13557).
-    BIP176: Bits Denomination [QT only] is supported as of v0.16.0 (PR 12035).
-    BIP325: Signet test network is supported as of v0.21.0 (PR 18267).
-    BIP339: Relay of transactions by wtxid is supported as of v0.21.0 (PR 18044).
-    BIP340 341 342: Validation rules for Taproot (including Schnorr signatures and Tapscript leaves) are implemented as of v0.21.0 (PR 19953), with mainnet activation as of v0.21.1 (PR 21377, PR 21686).
-    BIP350: Addresses for native v1+ segregated Witness outputs use bech32m instead of bech32 as of v22.0 (PR 20861).
-    BIP371: Taproot fields for PSBT as of v24.0 (PR 22558).
-    BIP380 381 382 383 384 385: Output Script Descriptors, and most of Script Expressions are implemented as of v0.17.0 (PR 13697).
-    BIP386: tr() Output Script Descriptors are implemented as of v22.0 (PR 22051).
