This document specifies a format for the export of labels that may be attached to various common types of records in a wallet.
==Copyright==
This BIP is licensed under the BSD 2-clause license.
==Motivation==
The export and import of funds across different Bitcoin wallet applications is well defined through standards such as BIP39, BIP32, BIP44 etc.
These standards are well supported and allow users to move easily between different wallets.
There is, however, no defined standard to transfer any labels the user may have applied to the transactions, addresses, public keys, inputs, outputs or xpubs in their wallet.
The UTXO model that Bitcoin uses makes these labels particularly valuable as they may indicate the source of funds, whether received externally or as a result of change from a prior transaction.
In both cases, care must be taken when spending to avoid undesirable leaks of private information.
In addition, many wallets allow unspent outputs to be frozen or made unspendable within the wallet. Since this wallet-related metadata is similar to labels and not captured elsewhere, it is also included in this format.
While there is currently no widely accepted format for exporting and importing labels, there are existing formats in use.
SLIP-0015<ref>[https://github.com/satoshilabs/slips/blob/master/slip-0015.md SLIP-0015]</ref> defines a format for exporting address and output labels, but requires encryption using a private key associated with the wallet seed, and thus cannot be used independently by coordinator wallets which cannot access private keys.
The Electrum wallet imports and exports address and transaction labels in a JSON format which could be used with other record types, but the format used is not self describing making record type identification difficult.
This allows a document to be split, streamed, or incrementally added to, and limits the potential for formatting errors to invalidate an entire import.
It is also a convenient format for command-line processing, which is often line-oriented.
Further to the JSON Lines specification, an export of labels from a wallet must be a UTF-8 encoded text file, containing one record per line consisting of a valid JSON object.
Lines are separated by <tt>\n</tt>. Multiline values are not permitted.
Each JSON object must contain both <tt>type</tt> and <tt>ref</tt> properties. The <tt>label</tt>, <tt>origin</tt> and <tt>spendable</tt> properties are optional. If the <tt>label</tt> or <tt>spendable</tt> properties are omitted, the importing wallet should not alter these values. The <tt>origin</tt> property should only appear where type is <tt>tx</tt>, and the <tt>spendable</tt> property only where type is <tt>output</tt>.
If present, the optional <tt>origin</tt> property must contain an abbreviated output descriptor (as defined by BIP380<ref>[https://github.com/bitcoin/bips/blob/master/bip-0380.mediawiki BIP-0380]</ref>) describing a BIP32 compatible originating wallet, including all key origin information but excluding any actual keys, any child path elements, or a checksum.
This property should be used to disambiguate transaction labels from different wallets contained in the same export, particularly when exporting multiple accounts derived from the same seed.
* An importing wallet may ignore records it does not store, and truncate labels if necessary. A suggested default for maximum label length is 255 characters, and an importing wallet should consider warning the user if truncation is applied.
