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+<pre>
+  BIP: Number not assigned
+  Layer: Applications
+  Title: Modern Hierarchy for Deterministic Multisignature Wallets
+  Author: Robert Spigler <RobertSpigler@ProtonMail.ch>
+  Comments-Summary: No comments
+  Comments-URI:
+  Status: Proposed
+  Type: Standards Track
+  Created: 2020-03-11
+</pre>
+
+===Copyright===
+
+This BIP is licensed under the 2-clause BSD license.
+
+==Abstract==
+
+This BIP defines a sane hierarchy for deterministic multisig wallets based on an algorithm described in BIP-0032 (BIP32 from now on), purpose scheme described in 
+BIP-0043 (BIP43 from now on), and multi-account hierarchy described in BIP-0044 (BIP44 from now on).
+
+This BIP is a particular application of BIP43.
+
+==Motivation==
+
+With the increase of more user friendly (offline) multisignature wallets, and adoption of new technologies such as 
+[https://github.com/bitcoin/bitcoin/blob/master/doc/descriptors.md the descriptor language] and [https://github.com/bitcoin/bips/blob/master/bip-0174.mediawiki 
+BIP-0174 (Partially Signed Bitcoin Transactions)] it is necessary to create a common derivation scheme that makes use of all new technologies.
+
+There are many issues with the current standards. As background, BIP 44/49/84 specifies:
+
+<pre>
+m / purpose' / coin_type' / account' / change / address_index
+</pre>
+
+where the BIP43 <code>purpose'</code> path is separate for each script (P2PKH, P2WPKH-in-P2SH, and P2WPKH respectively).  However, these per-script derivations 
+are made redundant with descriptors, which describe a collection of output scripts.  Note also that these are single sig derivations (which souldn't be reused for 
+multisig).
+
+Standardization is needed for multisig derivation paths.  There are some in existence, but all have issues.  For example, BIP45 specifies:
+
+<pre>
+m / purpose' / cosigner_index / change / address_index
+</pre>
+
+Like BIP44/49/84, BIP45 unecessarily demands a single script type (here, P2SH).  In addition, BIP45 sets <code>cosigner_index</code> in order to sort the 
+<code>purpose'</code> public keys of each cosigner.  This too is redundant, as descriptors can set the order of the public keys with <code>multi</code> or have 
+them sorted lexicographically (as described in [https://github.com/bitcoin/bips/blob/master/bip-0067.mediawiki BIP67) with <code>sortedmulti</code>.  Sorting 
+public keys between cosigners in order to create the full derivation path, prior to sending the key record to the coordinator to create the descriptor, merely adds 
+additional unnecessary communication rounds.
+
+There is an additional multisig derivation path in use "BIP"48 (there is no real standard), which specifies:
+
+<pre>
+m / purpose' / coin_type' / account' / script_type' / change / address_index
+</pre>
+
+Rather than having a separate BIP per script type after P2SH (BIP45), vendors decided to insert <code>script_type'</code> into the derivation path (where 
+P2SH-P2WSH=1, P2WSH=2, Future_Script=3, etc). As described previously, this is unnecessary, as the descriptor sets the script.  While it attempts to reduce 
+maintainence work by getting rid of new BIPs-per-script, it still requires maintaining an updated, redundant, script_type list.
+
+The hierarchy proposed in this paper is quite comprehensive. It allows the handling of multiple accounts, external and internal chains per account, and millions 
+of addresses per chain.
+
+Any script that is supported by descriptors (and the specific wallet implementation) is compatible with this BIP.
+
+This paper was inspired from BIP44.
+
+==Key sorting==
+
+Any wallet that supports descriptors inherently supports deterministic key sorting as per BIP67 (through the <code>sortedmulti</code> function) so that all 
+possible multisignature addresses/scripts are derived from deterministically sorted public keys.
+
+==Path levels==
+
+You should not be mixing keys and scripts. We define the following 5 levels in the BIP32 path:
+
+<pre>
+m / purpose' / coin_type' / account' / change / address_index
+</pre>
+
+<code>h</code> or <code>'</code> in the path indicates that BIP32 hardened derivation is used.
+
+Each level has a special meaning, described in the chapters below.
+
+===Purpose===
+
+Purpose is a constant set to XY' following the BIP43 recommendation.
+It indicates that the subtree of this node is used according to this specification.
+
+Hardened derivation is used at this level.
+
+===Coin type===
+
+One master node (seed) can be used for multiple Bitcoin networks.
+Sharing the same space for various networks has some disadvantages.
+
+Avoiding reusing addresses across networks and improving privacy issues.
+
+Coin type <code>0</code> for mainnet and <code>1</code> for testnet.
+
+Hardened derivation is used at this level.
+
+===Account===
+
+This level splits the key space into independent user identities, following the BIP44 pattern, so the wallet never mixes the coins across different accounts.
+
+Users can use these accounts to organize the funds in the same fashion as bank accounts; for donation purposes (where all addresses are considered public), for 
+saving purposes, for common expenses, etc.
+
+Accounts are numbered from index 0 in sequentially increasing manner.
+This number is used as child index in BIP32 derivation.
+
+Hardened derivation is used at this level.
+
+===Change===
+
+Constant 0 is used for external chain and constant 1 for internal chain (also known as change addresses). External chain is used for addresses that are meant to be 
+visible outside of the wallet (e.g. for receiving payments). Internal chain is used for addresses which are not meant to be visible outside of the wallet and is 
+used for return transaction change.
+
+Public derivation is used at this level.
+
+===Index===
+
+Addresses are numbered from index 0 in sequentially increasing manner.
+This number is used as child index in BIP32 derivation.
+
+Public derivation is used at this level.
+
+==Examples==
+
+{|
+|network
+|account
+|chain
+|address
+|path
+|-
+|mainnet
+|first
+|external
+|first
+|m / XY' / 0' / 0' / 0 / 0
+|-
+|mainnet
+|first
+|external
+|second
+|m / XY' / 0' / 0' / 0 / 1
+|-
+|mainnet
+|first
+|change
+|first
+|m / XY' / 0' / 0' / 1 / 0
+|-
+|mainnet
+|first
+|change
+|second
+|m / XY' / 0' / 0' / 1 / 1
+|-
+|mainnet
+|second
+|external
+|first
+|m / XY' / 0' / 1' / 0 / 0
+|-
+|mainnet
+|second
+|external
+|second
+|m / XY' / 0' / 1' / 0 / 1
+|-
+|testnet
+|first
+|external
+|first
+|m / XY' / 1' / 0' / 0 / 0
+|-
+|testnet
+|first
+|external
+|second
+|m / XY' / 1' / 0' / 0 / 1
+|-
+|testnet
+|first
+|change
+|first
+|m / XY' / 1' / 0' / 1 / 0
+|-
+|testnet
+|first
+|change
+|second
+|m / XY' / 1' / 0' / 1 / 1
+|-
+|testnet
+|second
+|external
+|first
+|m / XY' / 1' / 1' / 0 / 0
+|-
+|testnet
+|second
+|external
+|second
+|m / XY' / 1' / 1' / 0 / 1
+|-
+|testnet
+|second
+|change
+|first
+|m / XY' / 1' / 1' / 1 / 0
+|-
+|testnet
+|second
+|change
+|second
+|m / XY' / 1' / 1' / 1 / 1
+|}
+
+==Acknowledgement==
+
+
+==References==
+
+Original mailing list thread: TBD
+
+* [[bip-0032.mediawiki|BIP32 - Hierarchical Deterministic Wallets]]
+* [[bip-0043.mediawiki|BIP43 - Purpose Field for Deterministic Wallets]]
+* [[bip-0044.mediawiki|BIP44 - Multi-Account Hierarchy for Deterministic Wallets]]
+* [[https://github.com/bitcoin/bitcoin/blob/master/doc/descriptors.md - Output Descriptors]]
+* [[bip-0174.mediawiki|BIP174 - Partially Signed Bitcoin Transaction Format]]
+* [[bip-0067.mediawiki|BIP67 - Deterministic Pay-to-script-hash multi-signature addresses through public key sorting]]